Simplify api for running queues

By default just need taskqueue service to run all queues.
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.
*Needs a few unittests for the class.
Simplify example comments
Merge branch 'master' of wfgithub:WebFilings/furious into queue_runner_update
Change 1 to True to aid in readability
Rename _run_task to _execute_task
Rearrange code to make "public" functions more obvious
Add notes from review
Clean up mock instantiations
Attempt to improve 'run' logic readability
Merge pull request #77 from WebFilings/queue_runner_update

Queue runner update