Support for PostgreSQL 9.6

Problem Definition

PostgreSQL is now available:
https://www.postgresql.org/docs/9.6/static/release-9-6.html

Note: Bitbucket Server < 4.11 does not support PostgreSQL 9.6. If PostgreSQL is upgraded earlier, check the possible workarounds on the "Bitbucket Server fails to load pages due to "Could not get unique fields for table" errors" page.

Suggested Solution

Provide support for the PostgreSQL version 9.6.