Don't send refresh IE when unregistering.

git-svn-id: http://yate.null.ro/svn/yate/trunk@5515 acf43c95-373e-0410-b603-e72c3f656dc1
Set failure reason in call.execute when failed to start an outgoing call.

git-svn-id: http://yate.null.ro/svn/yate/trunk@5516 acf43c95-373e-0410-b603-e72c3f656dc1
Merge remote-tracking branch 'trunk' into upstream