[geary] (13 commits) ...Merge branch 'wip/766133-gnotification' into 'mainline'

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  49cd00f... Minor code cleanup (*)
  3d1032d... Migrated from libnotify to GLib notifications. bug 766133 (*)
  c0f5be2... Clean up desktop notification code (*)
  ef21ad5... Use app icon in notifications for consistency with other ap (*)
  3701aa0... Allow Notifications.Desktop to cancel its async tasks (*)
  f269e55... Don't play sounds when issuing a notifciation (*)
  dd3a7a1... Add API for (de)serialising FolderPath and EmailIdentifier (*)
  01a154b... Make it possible to distinguish between different folder ro (*)
  f748845... Make it easier to obtain folders from path objects from Gea (*)
  bb1fe53... Implement application actions for notifications (*)
  b80f6b0... Minor fix for MockObject (*)
  2e0ee8c... Ensure notifications are cleared on app activation (*)
  0aea07f... Merge branch 'wip/766133-gnotification' into 'mainline'

(*) This commit already existed in another branch; no separate mail sent