[bug 1035319] Switching from /vendor to peep.

This removes (most of) our /vendor directory and replaces the files with requirements files installable via peep[1]. Existing requirement files were also updated to be peep compatible, so we can use it for all of our package installations. Everything *seems* to work fine in my dev environment and all tests pass, other than some DeprecationWarnings. 

Finally, PIL was replaced with Pillow since we were already planning on switching and all these changes will need to be heavily tested on dev anyways. #1984 

r?