Remove the _osm_username cookie and session validation logic

This was a temporary hack to workaround issues with sessions getting
mixed up at the time of the rails 3.1 upgrade, but logs indicate that
whatever the original problem was it is no longer occurring.
Update to Leaflet 0.7
Update to latest Leaflet-hash plugin
Update to latest leaflet-osm plugin
Update to latest leaflet-locationfilter plugin
Localisation updates from http://translatewiki.net.
Merge branch 'master' into redesign

Conflicts:
	vendor/assets/leaflet/leaflet.hash.js
	vendor/assets/leaflet/leaflet.js