Remove the Gemfile.lock (closes #124)

According to [Yehuda](http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/), one should not commit the Gemfile.lock when a project is distributed as a gem.
Cleanup Travis yml
Lock to pessimistic versions in Gemfile and fix deprecations
Merge pull request #125 from opscode/sethvargo/remove_lockfile

[KNIFE-328] Remove the Gemfile.lock