Bug 1017333 - Clear notifications when we open the call log

Also don't clear notifications when we reopen the dialer app on another tab
when we do this we usually restore the hash in a teardown().
If you're a 100% certain that it's not needed I'm fine with that, but if the rationale is "travis is still green" I'd like to do the teardown just to make sure we don't have weird intermittents later.