Fix compilation error against current Gerrit master

EventDispatcher.postEvent() method now throws also
PermissionBackendExcepion which needs to be handled in order to not
produce compilation error.

Change-Id: I6eb1f85e4748283a5bf326c514eb09193b157f16
Signed-off-by: Dariusz Luksza <dluksza@collab.net>
1 file changed