start by fixing the hieradata syntax
Now make a stagecraft database
Add postgres stagecraft password from hiera
Allow access to stagecraft postgres database

Allow access to the stagecraft postgres database from the entire
performance platform cluster.
Add postgres client library and header files

Required for building the postgres python client, psycopg2.
Move postgres listen_address to postgres role

The address that the postgres machine listens on does not change between
environments.
Merge pull request #246 from alphagov/date_a_base

Add a postgres database for stagecraft