PostgreSQL/Postgis module

Introduce a PostgreSQL module capable of setting up databases in master
or slave mode, and postgis. Module also allows for setting up users both
in databases and pg_hba.conf

Module contains tests and rspecs.

Change-Id: I118a987de1c0ed38037cc3a15ba3fa2b299f55c4
Merge "PostgreSQL/Postgis module" into production