Add NoSQL database support for metering.

- Add two attributes to indicate whether NoSQL is used for metering
  database and the port used for NoSQL database.
- When database type is DB2, only NoSQL is supported and the SQL
  connection is not same to the one SQLAlchemy-based.

Change-Id: Icff805cee8e078f99ff46a59e290da60d2f9bb29
Merge "Add NoSQL database support for metering."