Fixed OverflowError when returning job IDs

[FlorianPerucki]

Some ObjectId objects may lead to an OverflowError when dumped using usjon.dumps() :

>>> ujson.dumps(ObjectId("568cf86d7bd78100822b9b2e"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: Unsupported UTF-8 sequence length when encoding string

[sylvinus]

Good catch! However output should stay JSON-encoded. You should use this instead:
https://github.com/pricingassistant/mrq/blob/master/mrq/worker.py#L346

[FlorianPerucki]

Nice, thanks!