MongoDB API updated

[antonis-papaioannou]

There is an error when trying to use mongodb driver:
AttributeError: 'module' object has no attribute 'Connection'

You have to use MongoClient instead of Connection (pymongo changed api).

You have to change line 236 of file drivers/mongodbdriver.py to:
self.conn = pymongo.MongoClient(config['host'], int(config['port']))

[apavlo]

Great! Can you send a PR?