Unusual documents are documents with different data
types for the data field. The data types include:
object, array, string and integer.
This PS makes necessary ORM model and schema
changes needed to support the different data types.
The ORM data type for the data column has been changed
to JSONB for PostgreSQL. Thus, DH now only supports
PostgreSQL. As a result, the tox jobs have been updated
to only use postgre.
Change-Id: I53694d56bef71adacb5eb79162678be73acb4ad8
69db7f81fa