Add parent and member associations for JayData's OData querying

* Fix the inverse property for modify_user in the Document entity
* Remove the Member associations from Folder to make the model simpler
* Move mime_type to the Document entity; it doesn't make sense in Folder
* Create associations for parent, create_user, modify_user and owner_user
  manually in the documents and folders collections
* Move the environment setting controlling JayData to the driver script
* Bumped version to 0.2.2