Improve setup.py version fetching in all packages as needed

[jeanconn]

See

#116 (comment)

[jeanconn]

Regarding putting the helper functions read, and find_version from

https://github.com/pypa/pip/blob/master/setup.py#L14

into testr. Two things:

1. testr right now is an optional dependence in most of our builds. Do we want to require it?
2. those routines would need a little customization for a non-local non-global here

And on a different track, would it make just as much sense to use 4. instead of 1. from:
https://packaging.python.org/guides/single-sourcing-package-version/
?

It seems that we could then just customize __version__ to be read/assigned from VERSION.

[taldcroft]

I'm still bitter that setuptools_scm turned out to be heavier than we'd like, but reviewing sot/cheta#157 it seemed to be in a working state.

Most of the "single-source" ideas including VERSION are not actually single-source given our package build process.

[jeanconn]

sot/cheta#157 looked to be in a working state, but I saw it didn't get merged and looks to not complete github build tests. Is the latter just due to the dual-package nature at this point?

[jzuhone]

What about versioneer?

https://github.com/warner/python-versioneer

It does require one to install their package in the Python stack, but after you run it on your package to generate the version-handling code, there are no new dependencies.

[taldcroft]

See sot/sparkles#129