Bug 1086277 - Add a test for add & delete a divider on homescreen

Generally I would prefer not to conflate tests like this but given that it's hard to change the divider before the setUp, I'm happy with @chirarobert method.

You also need to take into account that creating a new atom also creates new code that has to be maintained. With the atom there is two types of code doing almost exactly the same thing and thus more risk that one of them may regress and cause 2x bits of code to maintain.

In this case I think it's less risk to keep it the way @chirarobert has it now.