Error on json decode

[bl3tt3r]

Hello,
Firstly, thank you for this project.

We used your pack today and we're stuck with an error :

The content we send via rabbit for our tests :

Unless I'm mistaken, if the _deserialize_body function works and returns a dict, then the decode() function crashes in all cases.

Shouldn't the decode function be set before the _deserialize_body ?

[arm4b]

Could the .decode() be there in case when pickle is used?

stackstorm-rabbitmq/sensors/queues_sensor.py

Line 11 in e79bced

DESERIALIZATION_FUNCTIONS = {"json": json.loads, "pickle": pickle.loads}

I think it's worth enclosing .decode() in some try/catch, unless you see a better way.
Please open a PR to fix your issue anyway.