Adds tests, Travis-CI configuration and code data badges

* Adds tests for existing functionality
* Fixes incorrect `handlebars` reference in asset manifest
* Adds switch to `Gemfile` to handle Ruby versions prior to 1.9
* Adds badges for:
  * RubyGems (gem version)
  * Travis-CI (build status)
  * Gemnasium (status of gem dependencies)
  * Code Climate (code quality)
  * Coveralls (code coverage)