Use separate database by default for application tables

[bruth]

It is very common to have/want to connect to databases using a read-only connection. This is typically required when connecting to existing clinical systems or preferred when the database is being used by other systems and application tables would clutter the schema from other application's perspective.

The dependencies on this are:

• Add a harvest entry to the DATABASES setting in the Harvest template
• Add support to Avocado for using the non-default database when accessing it's data