Update PostgreSQL roles due to package version changes

This changeset updates the versions of PostgreSQL roles we use because new packages were cut for `libpq-dev` and `postgresql-9.3`. These changes will prevent errors when fresh provisions are attempted.
`azavea.postgresql-support` brings in the `main` repository channel from `apt.postgresql.org`. `main` is needed for `postgresql-client-9.3`, which gives us `psql`.