[TASK] Cleanup and fix spelling in variable names
[FEATURE] Add configuration of beanstalk server and tube in ext_conf
[FEATURE] Add some simple errorhandling

Add a new UnknownMessageException which is thrown whenever de message
from the queue does not implements the MessageInterface. Then wrap the
QueueWorker in a try/catch to fetch the error and proceed withot failing
completely.
A message that is failed is removed from the queue, so it is not retried.
[TASK] Add Github readme.rst file