Add fallback to distutils

[cooperlees]

• This is so we can build this in an environment that does not yet have
  setuptools
• Also added Python 3.6 as I built this with 3.6

[cooperlees]

Maybe time to also add 3.6 to travis 👌🏻

[adamjstewart]

Mostly a duplicate of #84. One of these two PRs should definitely be merged though.

[jaraco]

Although this workaround might help alleviate the issue, pip will still always attempt to build sdists with setuptools... so it may not help.

[adamjstewart]

pip will still always attempt to build sdists with setuptools

By attempt, do you mean that it will try to install setuptools from source first? If it uses a wheel, then that wouldn't be a problem. If it doesn't try to build setuptools from source, then wouldn't the fallback of distutils work?

P.S. I know next to nothing about pip and sdists, so I could be very mistaken.

[jaraco]

I mean it will uncoditionally import setuptools when building any sdist, which it will do in a subprocess of the current Python environment in whatever package state it happens to be in.

[cooperlees]

Why it may not help pip directly it will help people who run setup.py manually (with other automation) building from sdsts.

[zoofood]

Thanks Cooper. I'll bring it up to Python 3.6 as well. I used an earlier PR with the same fix. I hope this helps you out.