Removing EXPERIMENTAL.rst.
Adding a couple clarification docstrings.
Let's actually explain how this works.
Adding myself to contributors list.
Converting from str to six.text_type.
Fixing error handling such that processing is aborted if there is a single failure.

* Required switching sentinel values to integers -- since the objects
  are pickled when being pushed onto the queue, the value popped off
  of the queue will *not* be the same object.  Sad.
* When any single service fails, abort processing for all to avoid
  marking tasks handled by failed services as 'done'.
Improve logging during task-db manipulation.
Improve bitbucket error message.

.json is a bound method.  Calling it is not safe during error handling.