Fronts: new logic & rename collections into slices

This feature has already been code reviewed as part of:
#4055 #4026

This should be deployed during the course of today.

/cc @kungpochicken @stephanfowler @janua let me know when we are ready to go :bomb: 

![ ](http://media.giphy.com/media/llnl3XD1JNttu/giphy.gif)