Multiple improvements to World.run*() methods

[jopereira]

Original issue 18 created by jopereira on 2013-08-26T09:39:05.000Z:

The API would become easier to use with the following improvements:

1. Add method runAny(...), that run simulation until some milestone has been achieved.
2. Allow driver code to obtain milestone completion time.
3. Allow runAll(...) to be ignore Entry milestones without pending invocations. These should be ignored instead of throwing or blocking execution.