Introduced a property on the test actor that can change the speed of animations

This can be used in `beforeEach:` and `afterEach:` to decrease execution
time by making animations run faster and not having to wait as long for
these animations to complete. 

Two example cases where this can matter are:
 - orientation changes
 - keyboard appearing 

Note that the current behaviour and wait durations are the same if this property not altered.