css: Fixup bubble font sizes
placeStore: Don't call _store during database loading

https://bugzilla.gnome.org/show_bug.cgi?id=726625
placeStore: Add osm-id as unique identifier

The name of a place might change in OpenStreetMap or through code
changes in geocode-glib. It is safer to use the osm-id to assert the
uniqueness of a place.

https://bugzilla.gnome.org/show_bug.cgi?id=726625
placeStore: Change updateAddTime to updatePlace

Since the name and location of place could change, make sure
we update the place on re-visit and just not the add time.

https://bugzilla.gnome.org/show_bug.cgi?id=726625