Remove `refresh` action on saving an edit

It seems to bring us back to the previous routes, which messes with the animations.
Transition to ItemsRoute after saving a new item

Makes animations simpler and it also just makes sense.
Leave destroying the GroupEdit and GroupsNew model to willTransition
"Back" button in GroupIndex template transitions to GroupsRoute

Seems more intuitive as a "back" button, even if transitioning to ItemsRoute was more functional.
Abstract most ItemViewRoute methods into a ViewRouteBase module
Make mobile animations and transitions work for Group-related routes
Remove some old logic from ItemsRoute from a previous animation method
Update ItemsRoute animation and transition logic
Update seed data
Detect form factor with matchMedia using min- and max-device-width
Don't animate transition from ItemsRoute to GroupsRoute if not on small screen