Remove Gemfile.

The presence of a Gemfile without a Gemfile.lock seems to aggregate
heroku-based deployment from travis-ci.  Since this is a Python project
there really is no need for one anyway.
.travis.yml: Only deploy from the Python 3.4 build.
Merge pull request #2 from dave-shawley/only-deploy-from-3.4

Only deploy from 3.4