Don't install in /opt/graphite anymore, this is just strange and causes nothing
but trouble. Setuptools does not support it either.

Switch to setuptools to get rid of following warnings:
UserWarning: Unknown distribution option: 'install_requires'
UserWarning: Unknown distribution option: 'long_description_content_type'

Synthesize is not being updated anymore (latest version is 1.0.2). Removing
it from the docs to not confuse users. And we have an official docker image now.

The GRAPHITE_ROOT was to be set to the parent directory of the path where
graphite-web is installed. The `storage`, `static` and `content` directories are
set to be dubdirs of GRAPHITE_ROOT.

If installing Graphite in the regular Python path's this would make the directories
look something like `/usr/lib/python3.7/{storage,static,conf}`. Which is probably not
what the user wants.

This sets the default to `sys.prefix`.

sys.prefix

Installing the static assets in the project directory instead of an external directory
make installation easier.

Add whitenoise to requires in setup.py so that the static assets are automatically (without
user action) served after installation.

Remove package_data from setup.py, you should use package_data or MANIFEST.in to specify
which non-python files have to be installed, not both.

…_settings.py

Fixes dashboards which were broken with last commit

Fix some spelling