Fix test_that_posting_question_works because it doesn't wait for the cor...

...rect page title.

The test failed in the latest [run][link] because the actual page title was hard coded before the page refreshed. 
Also removed an assert because it's the same as the wait from the framework.

@AndreiH r?

[link]:http://selenium.qa.mtv2.mozilla.com:8080/view/SUMO/job/sumo.stage/1703/HTML_Report/