Revert "Specify ruby version in Gemfile"

This reverts commit 7dd79afa8d22e6d937af6363828d38c40fb8aa36.

Seems like heroku doesn't like Arch version of ruby (2.1.0p0) and I don't want
to run two different version so let's just have the warning when deploying to
heroku
Fix favorite_brewery and favorite_style
Remove unnecessary command from travis.yml