Merge outstanding PRs

* Merges all outstanding PRs, adding support for python 3 and pypy
* Fixes merge conflicts with master
* Adds travis and tox support for testing

Note: cache tests are skipped in python 3 and pypy due to gevent requirement. This can be fixed by swapping asis out in favor of responses, httparty, etc.
I believe @dlecocq suggested switching this to `>= 1.5, != 2.0`.