Platform requirements reorg

This work is motivated by general code hygiene concerns and moving toward building all ansible managed, and maybe all, environments using pip wheel packages.

This has been tested with the full stack, cf., http://jenkins.edx.org:8080/job/ansible-provision/164/ 

- removes requirements file includes entirely.
- moves leaked github requirements in base.txt into github.txt, these have not revision, which is a problem.
- adds additional files that were included into pavers pre-reqs
- removes distribute entirely
- experimentally makes local installs use wheels, may need to roll this back, but works in ansible land, would be super if we could pull these out of platform entirely.

@jarv @feanil @hkim823 @singingwolfboy @cpennington Please let me know your thoughts, there will be a related configuration PR to follow.