Modifies goto so it only returns with wait=True when stage has arrived (controller.py)
Modifies goto so it only returns with wait=True when stage has arrived (controller.py)

By arrived I mean that when goto is used with wait=True, by the time it
returns, querying the controller's position using status will return a
position exactly equal to the position requested.

vascotenner/pyAPT,anthonyclays/pyAPT,weinshec/pyAPT