Merge pull request #47 from flexminder/master

Log error backtraces
Allow passing of arguements to RMQ plugins
Merge pull request #49 from Donavan/master

Allow passing of arguements to RMQ plugins
Rename worker arguments to match the names used by Bunny
Allow publishing with all options accepted by Bunny

Previously Sneakers cherry-picked out a few options to pass to Rabbit,
and discarded the rest. This makes it impossible to perform some useful
operations, such as adding meta data to a message, or settings its TTL.
Since Sneakers goes out of its way to allow workers to ready from the
metadata sent by Rabbit, it doesn't makes sense for it to forbid its
workers from publishing metadata.
Respect RABBITMQ_URL if its set.
Merge pull request #52 from flexminder/use_rabbitmq_url_as_default

Respect RABBITMQ_URL if it's set.
Merge pull request #54 from flexminder/improve_worker_variable_names

Rename worker arguments to match the names used by Bunny
Merge pull request #53 from flexminder/allow_all_publishing_options

Allow publishing with all options accepted by Bunny