Update Travis config: drop 1.8.7, add 2.0 and 2.1
Remove extraneous development dependencies from Gemfile
Switch to now-released omniauth-foursquare 1.0.1

It includes our fixes for the info hash
[gem] Upgrade thinking-sphinx to 3.1.0
Add puma for deployment on new server
Set up Capistrano 3 for basic deployment to new server
Compile assets when deploying