re-create the actions menu only when needed: when we popup it up, and only when one account has signed in or signed out

fail with TB, instead of segfault

(gajim may die with older dbus - it is not
completely tested)

(0.23 is not supported)
get cached vcards, instead of signaling server

argument [account] returns a valid result

to be printed

This should help WMs like ion "do their thing" easier.

message when there are no command arguments

in this case we wait only for close events