Set the popup grab button as pressed only if it actually is

This ensures the popup_grab.initial_up field isn't reset to 0
if the popup was not opened because of a mouse press but because
of moving the mouse with a popup already open. Not doing so will
make the first click outside the client area go ignored.
Force position for shell toplevel surfaces

Some surfaces such as indicators' menus and AppChooser need to
force their position. This is not supported by Wayland, clients
create surfaces and only specify the size, hence we need a new
request to force the position.
Rename interface to hawaii_desktop_shell

Avoid confusion with Weston's desktop_shell interface.
Revert "Fix wl_notification_daemon"

This reverts commit 5b9d4eb9d6d8e4dcbb257375ea1f76f1a47122a2 which
didn't really fix anything.

The crash I was experiencing was in wl_notification_add_surface()
and it was caused by the fact that when it was called, the notification
surface wasn't attached yet.