Use API for Prefs UI menu generation.

Use API for Prefs UI menu generation.

Additionally, at least for DIMP, make Growler notification work again.
However, this will only work for IMP options - once a user moves to
another app's options, the regular notifications will be used. Pretty
much means we will have to build a prefs-only Growler notification
handler that doesn't rely on any specific AJAX app to be loaded.