Add a way to specify multiple schedules for the same test

[alexdoth]

Currently in order to specify multiple schedules for the same test, one needs to duplicate the test and invoke setSchedule with the desired order for the particular test.

A more desirable use would be to specify the schedules for the test, and then execute the test multiple times for the given schedules.

An example description could be:

"My Actor" should {
   "complete operation X" in {
       // test source code
    } with Schedule(message1 -> message2 -> message3)
      with Schedule(message2 -> message3 -> message1)
      with Schedule(message3 -> message1 -> message2)
}

And when a test fails, a description for which schedule the test failed could be printed to the console.