Add Check-in capabilities

This only adds check-in capabilities necessary
to implement a check-in UI.

https://bugzilla.gnome.org/show_bug.cgi?id=731113
Add Check-in dialog

https://bugzilla.gnome.org/show_bug.cgi?id=731113
mapBubble: Add Check-in button

https://bugzilla.gnome.org/show_bug.cgi?id=731113
userLocationBubble: Enable Check-in button

https://bugzilla.gnome.org/show_bug.cgi?id=731113
Overpass: use https

https://bugzilla.gnome.org/show_bug.cgi?id=741409
Updated Hebrew translation
Remove the socialService directory
Release 3.15.3
utils: Handle all loadable icons
Add c shim library
Convert searchResultMarker to placeMarker
mapView: Add gotoBBox helper
mapBubble: Do not convert to Place
Add busyMarker module
mainWindow: add markBusy method
Add contact module
Add 'show-contact' action