UITestHarness usage of UIPrompt should be configurable

The UIPrompt in the UITestHarness always returns default values. It should be possible to override these values so the test can have a deterministic behavior.

I propose the inclusion of a Map<String,String> attribute to UITestHarness in which the key will be a regexp to the message shown when calling UIPrompt.prompt(String message) and the value the value to be returned