panelMenu: Use the accessible-name property instead of a label actor

We already have code for this in StWidget.

https://bugzilla.gnome.org/show_bug.cgi?id=705898
panel: Rewrite the app menu to use the new "sync" pattern

The existing app menu was a kludge of legacy code that tried to manage
a bunch of state, and had a number of issues:

 * It didn't properly manage visibility when combined with multiple
   apps and the overview.

 * It didn't properly manage reactivity when tabbing away from a busy
   app to another app.

 * It didn't properly disconnect signals when going from one app
   to nothing.

and countless others. Rewrite it to use the new "sync" code pattern,
where we centralize all state management and do transitions from that,
rather than strange and quirky control flow.

https://bugzilla.gnome.org/show_bug.cgi?id=705898
messageTray: Move adding the menu actor to MessageTrayContextMenu

This matches BackgroundMenu and EntryMenu.

https://bugzilla.gnome.org/show_bug.cgi?id=699272
messageTray: Use a PopupMenuManager for the message tray context menu

https://bugzilla.gnome.org/show_bug.cgi?id=699272
messageTray: Rename the context menu to the tray menu

https://bugzilla.gnome.org/show_bug.cgi?id=699272
Updated POTFILES.in
Tajik translation updated
Updated Spanish translation
Updated Norwegian bokmål translation
Updated translation for Afrikaans (af)
Updated Czech translation
modalDialog: The dialog layout should expand, not the buttons

https://bugzilla.gnome.org/show_bug.cgi?id=705916
network: Add an empty state to the wifi dialog and adjust the sizing

https://bugzilla.gnome.org/show_bug.cgi?id=705916
screencast: Use sessionUpdated as our method name

This is what we consistently use everywhere else.
components: Remove the built-in recorder keybinding and component

The keybinding is now part of gnome-settings-daemon
Add a screencast indicator for when we're recording

This will replace the indicator painted on the stage right now.

This unfortunately does not work for the recorder triggered by the
keybinding -- we'll simply replace the in-shell code with a keybinding
powered by gnome-settings-daemon.
data: Remove leftover keybindings definition
Updated POTFILES.in
Tajik translation updated
popupMenu: changes rotation center of sub-menu's triangle

When the triangle rotates (when sub-menu is expanded), it seems as if
the triangle pivots from one corner even though rotation center is set
to Clutter.Gravity.CENTER. Hence the rotation center is set nearer to
the edge than to the corner ([0.3, 0.5] instead of [0.5, 0.5]) so that
it doesn't appear odd.

Also pivot_point is used instead of rotation_center_z_gravity as it is
deprecated.

http://bugzilla.gnome.org/show_bug.cgi?id=703109