Merged postgres command into environment command; remove all PGO artifacts...

Merged postgres command into environment command; remove all PGO artifacts when postgres is disabled in the namespace

Closes #16 (closed)

The step to set labels on the namespace should not delete PGO labels, so moved that logic from postgres command to environment command, which in turn required more postgres logic to be copied to environment. Ultimately the best solution was to merge the commands completely, which makes more sense anyway.