Use bundler/bower to manage dependencies

* Add Gemfile[.lock] with proper version constraints
* Add bower.json/.bowerrc
* Configure sass
* Update README
Add font-awesome, compass-validator gems
update travis-ci config
No need to run 'bundle install' in travis-ci before script
Mention that 'bower install' must be manually run
install bower first (travis-ci)
 event-date-small in mobile tablet view
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