Revert "Use PostgreSQL 9.3's `pg_isready` to wait for connectivity"

Reverting postgres superuser changes until after stable.

This reverts commit e2066841106a6b89093ab685368742efa4e3c2c1.
Revert "Create the 'postgres' superuser"

Reverting postgres superuser changes until after stable.

This reverts commit 7de29bd26f5e514e95d5d261c08f3029337eecb3.
Revert "postgresql: properly fix permissions issue by in postStart"

Reverting postgres superuser changes until after stable.

This reverts commit c66be6378d8bbcea271b2d2102741fdda87ec8fe.
Revert "Merge branch 'postgresql-user' of git://github.com/ocharles/nixpkgs"

Reverting postgres superuser changes until after stable.

This reverts commit 6cc0cc7ff6136963acb32b5107696484b6220562, reversing
changes made to 3c4be425dbe2d5a00f2923210a86ce7e7a4c516f.
Merge branch 'revert-postgres-superuser'

The recent postgres superuser changes have caused a lot of breakages to
existing systems, and we are very close to branching for the 14.04
stable release. We can bring this back after.