fix for LinkedKilled error

darcs-hash:20090113102103-b2873-b71cdc570f4b5eac97a64a04025e969b4923573c
Added parse_sip_uri method to PJSIPUA to wrap PJSIP SIP URI parsing

darcs-hash:20090113131521-58103-10c14ff28d65fe49595652f43feaa1a3e84b9fe8