Fix ShellAppSystem's use of no_focus_window, clean up state handling

First, we were passing an incorrect timestamp to
meta_display_focus_the_no_focus_window - fix that.

The invocation of set_focus_app to the started app there couldn't
really work, because (if the above call had worked) we'd get the
X reply *after* the started app.

What we need to untangle here is the distinction that's now made in
ShellApp between _STATE_STARTING and _STATE_RUNNING.  A nice way to
start doing this is to rebase ShellWindowTracker to only be concerned
with app states.  Concretely, the current "has windows implies
running" logic now lives just inside shell-app.c.

Rename the app-running-changed signal to be app-state-changed.  This
will ultimately be useful so that inside the panel, we can track
the last started app.

https://bugzilla.gnome.org/show_bug.cgi?id=620899

js/ui/panel.js

@@ -697,7 +697,7 @@ AppMenuButton.prototype = {
         // cases where the focused window's application changes without the focus
         // changing.  An example case is how we map Firefox based on the window
         // title which is a dynamic property.
-        tracker.connect('app-running-changed', Lang.bind(this, this._sync));
+        tracker.connect('app-state-changed', Lang.bind(this, this._sync));
 
         this._sync();
     },