docs: Detail project setup and contributing workflow (pyronear#8)

* Add new table of contents to precise project setup & contributing workflow

* Add explanation on how to create a virtual environment

* Add section to detail how to fork project and install dependencies

* detail step-by-step the current contributing worklow

CONTRIBUTING.md

@@ -32,14 +32,155 @@ Use Github [issues](https://github.com/frgfm/PyroNear/issues) for feature reques
 
 ## Code contribution
 
-In order to contribute to the project,
+In order to contribute to  project, we will first **set up the development environment**, then describe the **contributing workflow**.
 
-- Fork the repository
-- Create a new branch with the name of your feature
-- Make your commits (remember to add unit tests for your code)
-- When satisfied with your branch, open a [PR](https://help.github.com/en/articles/creating-a-pull-request-from-a-fork) from your fork
+* [Project Setup](project-setup)
+
+    _How to set up a forked project and install its dependencies in a well-encapsulated development environment_
+    1. [Create a virtual environment](#create-a-virtual-environment)
+    2. [Fork the project](#fork-the-repository)
+* [Contributing workflow](contributing-workflow)
+
+   _How to pull remote changes/new contributions and push your contributions to the original project_
+
+* [Code & commit guidelines](#commits)
+
+### Project Setup
+---
+In order to enable every one to fluently contribute to the project, we are going
+to set up the project properly following some steps:
+1. **Create a virtual environment** to avoid collision with our OS and other projects
+2. **Fork the project** to be able to start working on a local copy of the project
+
+#### 1. Create a virtual environment
+We are going to create an python3.6 environment with dedicated to Pyro project. We'll use [virtualenvwrapper](https://virtualenvwrapper.readthedocs.io/).
+
+Please open a terminal and follow the instructions.
+```shell
+# install package
+pip install virtualenvwrapper
+
+# add at the end of your .bashrc
+export WORKON_HOME=$HOME/.virtualenvs
+export PROJECT_HOME=$HOME/Devel
+source /usr/local/bin/virtualenvwrapper.sh
+
+# list available virtual environments
+workon
+
+# create new environment dubbed "pyro36" using python 3.6
+mkvirtualenv -p $(which python3.6) pyro36
+
+# activate pyro36 environment
+workon pyro36
+
+# deactivate the current environment
+deactivate
+
+# delete virtual environment (only do it if needed)
+rmvirtualenv pyro36
+```
+
+#### 2. Fork the repository
+We are going to get a local copy of the remote project (_fork_) and set remotes so we stay up to date to recent contributions.
+
+1. Create a fork by clicking on the **fork button** on the current repository page
+2. Clone _your_ fork locally.
+```shell
+# change directory to one for the project
+cd /path/to/local/pyronear/project/
+
+# clone your fork. replace YOUR_USERNAME accordingly
+git clone https://github.com/YOUR_USERNAME/PyroNear.git
+```
+
+3. Set remotes to original project and merge new contributions onto master.
+```shell
+# add the original repository as remote repository called "upstream"
+git remote add upstream https://github.com/frgfm/PyroNear.git
+
+# verify repository has been correctly added
+git remote -v
+
+# fetch all changes from the upstream repository
+git fetch upstream
+
+# switch to the master branch of your fork
+git checkout master
+
+# merge changes from the upstream repository into your fork
+git merge upstream/master
+```
+
+4. install the project dependencies
+```shell
+# install dependencies
+pip install -r requirements.txt
+
+# install current project in editable mode,
+# so local changes will be reflected locally (ie:at import)
+pip install -e .
+```
+
+
+
+### Contributing workflow
+---
+Once the project is well set up, we are going to detail step by step a usual contributing workflow.
+
+1.  Merge recent contributions onto master (do this frequently to stay up-to-date)
+```shell
+# fetch all changes from the upstream repository
+git fetch upstream
+
+# switch to the master branch of your fork
+git checkout master
+
+# merge changes from the upstream repository into your fork
+git merge upstream/master
+```
+
+Note: Since, we are going to create features on separate local branches so they'll be merged onto **original project remote master** via pull requests, we may use **pulling** instead of fetching & merging. This way our **_local_ master branch** will reflect **_remote_ original project**. We don't expect to make changes on local master in this workflow so no conflict should arise when merging:
+```shell
+# switch to local master
+git checkout master
+
+#  merge remote master of original project onto local master
+git pull upstream/master
+```
+
+2. Create a local feature branch to work on
+
+```shell
+# Create a new branch with the name of your feature
+git checkout -b pioneering-feature-branch
+```
+
+3. Commit your changes (remember to add unit tests for your code). Feel free to interactively rebase your history to improve readability. See [Commits section](#commits) to follow guidelines.
+
+4. Rebase your feature branch so that merging it will be a simple fast-forward that won't require any conflict resolution work.
+```shell
+# Switch to feature branch
+git checkout pioneering-feature-branch
+
+# Rebase on master
+git rebase master
+```
+
+5. Push your changes on remote feature branch.
+```shell
+git checkout pioneering-feature-branch
+
+# Push first time (we create remote branch at the same time)
+git push -u origin pioneering-feature-branch
+
+# Next times, we simply push commits
+git push origin
+```
+
+6. When satisfied with your branch, open a [PR](https://help.github.com/en/articles/creating-a-pull-request-from-a-fork) from your fork in order to integrate your contribution to original project.
 
 ### Commits
 
 - **Code**: ensure to provide docstrings to your Python code. In doing so, please follow [Google-style](https://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html) so it can ease the process of documentation later.
-- **Commit message**: please follow [Udacity guide](http://udacity.github.io/git-styleguide/)
+- **Commit message**: please follow [Udacity guide](http://udacity.github.io/git-styleguide/)