Makes test stable and adds helper comparison methods

* Takes into account that the timer can be triggered multiple times before the initial request is done (especially if the server is slow)
* Adds assertLessThan, assertLessThanOrEqual, assertGreaterThan, assertGreaterThanOrEqual to ease test creation

Change-Id: I5ce1681e35d9c1de02a83b38528f17ee705331d7