Update to use the new Twitter 5.0.0 gem.
adding pessimistic versioning for gem dependencies
adding haml to dev dependencies so all tests run
switching from test unit to minitest
moving cli to lib and updating bin file
adding simplecov for verifying test coverage
moving app to it's own file under lib/dashing
light refactoring for better test coverage
updating javascripts path
removing and ignoring .ruby-version
Merge pull request #296 from Shopify/updating_gems_and_refactoring

Updating gems and refactoring