Set postgres_install and postgres_create_database false

Set postgres_install and postgres_create_database equal to false so that
by default the database isn't created and postgres isn't installed. For
some reason even though the environment is set correctly in the
deployment files within the academy project, the database is still
trying to create itself
Merge pull request #15 from nwwatson/academy

Set postgres_install and postgres_create_database false