ContactPane: Update right titlebar after editing contact

introduced a signal display_name_changed to notify listeners and especially to update the right titlebar after the name of a contact has been changed to fix issue #78
1 job for master in 10 minutes and 44 seconds (queued for 5 minutes and 50 seconds)
Status Name Job ID Coverage
  Build
passed build-gnome-contacts #5817

00:10:44