schema versioning

[geomat0101]

need something that mediamgr.models.connect can check to see if the schema needs to be updated.

• set version in mediamgr.schema at either module or preferably collection and graph levels
• when connect() creates the schema, it stashes the version somewhere in a special arangodb state collection
• future connects compare schema versions and if different the schema is re-applied via collection.configure and indexes get checked