Fixes hash handling issues

* Fixes the bug where the browser hash would get nuked on
foreign anchor clicks
* Moves the hash handling back into the mmv itself
* Adds test coverage for the hash nuking bug

Change-Id: Iea57d0f4b9090f96e622418223d3f774923e8038
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/254