Extension methods for Backbone.Collection
* sortWith: sort collections like Array#sort
* sortOn: sort models by the specified attribute
* reverseSortOn: reverse sort models by the specified attribute
Reworking the API with advice from @tbranyen
* "willNavigate" is now "before"
* "didNavigate" is now "after"
* Events are now triggered from the Backbone.Router instead of Backbone.History
* Renamed as `routerEvents()`