[Resolves #894] Switch to using poetry

[zaro0508]

The intent here is to change the tooling over to use poetry instead of setuptools.
This is building on the work that was started by @tarkatronic in PR #1035

Some important things to note:

• Poetry will be used for packaging, dependencies, and publishing.
• Poetry is smart enough to automatically include data files such as the *.json that had to be manually included by setuptools.
• twine is no longer necessary as we can simply use poetry publish.
• Poetry handles all virtualenv matters automatically. So we no longer need to instruct users to construct virtualenvs for development purposes, nor do we need to manually create and manage them for CI.
• Dependency specifications are a bit different with Poetry, and a bit more "modern", as seen here.
• I have told git (via the .gitattributes) file to treat the poetry.lock file as binary. This is a fairly standard practice, also followed in the JS community with the package-lock.json file. This does two primary things:
  • Tells GitHub to not attempt to display a diff for this file
  • Prevents frequent merge conflicts, since this tends to be a frequently updated file

[zaro0508]

@jfalkenstein i got unit tests working for python 3.7 now as well.

[jfalkenstein]

I hope to test this some evening this week. Sorry for the delay.

[jfalkenstein]

I think the troposphere extra is implemented improperly (or at least weirdly). It should also be a dev dependency.

Also, the github pull request template references running make test.

Finally, I think it's a pretty significant loss with losing the makefile. I really feel like the makefile didn't have to be removed and it should have just been updated.

[jfalkenstein]

It also appears as if integration tests are failing on this.

[jfalkenstein]

I'll try to test this out tonight.

[jfalkenstein]

This looks good to me now. I'm running integration tests on it now. Assuming all tests pass, I'll approve.

[jfalkenstein]

Congratulations.