Simplify api for running queues

By default just need taskqueue service to run all queues:
    run(taskq_service)
Don't need to deal with queue descriptions, just names.

Replace "execute" with "run".
Keep track of the number of tasks run.
Create an optional simple class Runner for holding state.
Added integration test.

*Not quite done, needs a few unittests for the class.

@robertkluin @beaulyddon-wf @johnlockwood-wf @tannermiller-wf