Revert "Have travis test against python3.6"

This reverts commit 3da914f.

These commits got 3.6 working on travis, but broke 3.5 (go figure).
It is the python interpereter in travis that is broken, not this code,
and I'm too lazy to deal with it right now. I'll try again later

Author: vimalloc

.travis.yml

@@ -7,7 +7,6 @@ env:
     - TOXENV=py33
     - TOXENV=py34
     - TOXENV=py35
-    - TOXENV=py36
 install:
     - pip install -U pip
     - pip install -U Flask PyJWT six tox coverage coveralls