[UI] changed visibility of menu entries

Some menu entries makes no sense when XMPP mode is not used. Those
entries are no longer displayed.

Also removed some (NOT connected) labels as it is not very helpful as
long as a user do not know what button he/she must actually press to
connect.

Change-Id: I1c0a096a4da85ed6d63f57a8345bd7dcbd79718e
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1631
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>