Add all streams in one collection

Following modifications are introduced in the MongoDB structure:

• All streams for given data source are saved in one collection
• new field message_id is used to save message id in data collection
• inprocess_ collection also contains all streams. New fields message_id, stream and group_id are added
• Indeses are created for data_, acks_ and inprocess_ collections
• In order to keep back compatibility a message have to be modified before being returned:
  • copy message_id to _id
  • copy message_id to _id for messages of dataset
• All acknowledged messages added to the same collection
  • New fields group_id and stream are added