QA: replace hard-coded 7 seconds sleep with poll method

The step formerly know as "I come back from grabbing a cup of coffee"
is replaced by a step that reloads the page a number of times, where
that number may be set by the user.  If the notification has arrived,
the polling stops and the test continues.

In practice with a local browser pointed to beta labs, the
notification is arriving in plenty of time for the first page load
and I do not see the page reloading at all.

Change-Id: I95dd77d4f5525645e46244e40bfcd86e9124f3b1
Merge "QA: replace hard-coded 7 seconds sleep with poll method"