Store Router.location in container.

This was suggested in #3702, but since that PR targeted the beta branch
we decided not to make significant structural changes.

This enables the location to be looked up from the container (instead of
manually created).

Deprecates usage of `Ember.Location.registerImplementation`.
Merge pull request #3752 from rjackson/store_location_in_container

Store Router.location in container.