placeStore: store place bounding_box

https://bugzilla.gnome.org/show_bug.cgi?id=722865
Use Place instead of Location in mapLocation

https://bugzilla.gnome.org/show_bug.cgi?id=722865
mapLocation: use placeType in zoomToFit

https://bugzilla.gnome.org/show_bug.cgi?id=722865
mapLocation: use place bbox for ensuring visible

Use the bounding box of the GeocodePlace in the ensure
visible operation. This will make sure that we reach a
zoom-level that includes the whole of the new place we
are travelling to.

https://bugzilla.gnome.org/show_bug.cgi?id=722865
mapLocation: set zoom-level to cover place bbox

Find and use the first zoom-level that covers the place
bounding box.

https://bugzilla.gnome.org/show_bug.cgi?id=722865