improv: update and simplify dependencies

Update gems. Move to Ruby 2.0

[3:00]
fix: remove buggy Facebook integration

[0:30]
Merge pull request #325 from zaiste/deps-1

Updated dependencies
Update .travis.yml

Gemfile force to use ruby 2.0.0, so we need to test it on travis with the right ruby version.
Merge pull request #326 from arthurnn/patch-1

Update .travis.yml
fix: add `spork` gem into `test` group
fix: add `unf` gem

Needed for `rake db:migrate` task