Bug 1086676 - Add a test to check notification when you miss a call from...

... a known contact
Step 3 of the test case says 'Verify the user sees a missed call notification message and the known contacts info is shown.'
In order to do that, you can use the methods in https://github.com/mozilla-b2g/gaia/blob/master/tests/python/gaia-ui-tests/gaiatest/apps/lockscreen/app.py#L94 (to check the title + content of the notification)