Add view location page

* Users can view individual locations on a map.
* Change variable names in add location page for readability.
* Move marker icon declarations to the top so they are easier to find
and change.
Add add to playlist page

* Implement byroredux's API to provide title suggestions to users when
adding games.
* Refactor handler code so that exceptions occur before entities
are written to the datastore, obsoleting conditional entity key delete
logic.
* Reorganise code for readability.
* Delete geohashes when deleting locations.
* Add Google API key to map pages.
* Add playlist/wishlist counters to Person model.
* Add PlaylistGame model to store user game information.
* Add add to playlist page.
* Users can add games to Playlist.