MapLocation: Add route search button

Make it possible to make simple route searches via location bubbles.
More advanced searches will have to be made via the sidebar.

https://bugzilla.gnome.org/show_bug.cgi?id=728695
MapView: cleanup _init

Split out some of the mapView initialization into its own _init* methods.

https://bugzilla.gnome.org/show_bug.cgi?id=728695
Split out geocode to its own service

This is needed for when you want to perform a geocode query without
access to MapView.
Update: RouteService

 - Make fetchRoute take GeocodePlace instead of a coordinate.
 - emit 'updated' instead of 'change'

Squash with:
  876117b Add RouteService module
Update: Route

Remove unneeded parameter

Squash with:
  7d6d3b1 Add Route query model
Update: RouteQuery

Some changes to the routequery needed for the bind_property stuff that I
didn't anticipate.

 - Change signal from change to updated (and use glib signals)
 - Add setters and getters that does notify() calls
 - some small refactorings

Squash with:
   7d6d3b1 Add Route query model
Add a sidebar for route interaction

This is a total re-implementation of the sidebar for searching and
interacting with routes.