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)