Add support for jabber audio calls via libjingle for all jabber accounts

Current version of libjingle library included in kopete tree supports both
google libjingle and real jingle protocol. It also supports connecting to
other (non google's) jabber servers (via special --s flag), but does not
support SRV dns lookups of jabber host name.

This patch enabling libjingle audio call support for all jabber accounts
(not only google) and adding code for xmpp-client SRV lookup which is
needed by external libjingle call application.