closes #1421

Thanks to Heather Gilmore, my wife, for grey-scaling the image. :-*

use of the interators to jide more of the underlying details.

catch icq. and icq but not icqsucks.org as jid that relates with transport. thx to knuckles for the idea

get_actor --> get_name_from_jid so it is visible it is on gajim level and not on xmppy (lower) lever

custom appications vbox only shows up when we select Custom. this cleans up UI by making it more robust and less confusing and gains  in height of contents of advanced tab in prefs window