Make drawHierarchyInKeyWindow default to true when running hosted tests

[DavidBrunow]

I'm not sure how this would be implemented, but thoughts on defaulting drawHierarchyInKeyWindow to true if the tests are running inside a host application?

We've been using this library for over a year and using a host application for our tests for over nine months. Until recently I did not know that I had to set drawHierarchyInKeyWindow to true in addition to running inside a host application in order to get the most accurate rendering.

This situation might also be improved by documentation that talks through the behavior of host applications and the drawHierarchyInKeyWindow -- I've created a pull request for that here: #796