PostgreSQL 9.3.1

- Use sha256 instead of sha1, because the upstream download site
  provides the former.

- Remove various workarounds for PL/Python build issues.  These have all been fixed upstream.
postgresql::db no longer requires an Exec
Couple $datadir and $logdir to Postgres minor version
Forgot about tests :disappointed:
Merge pull request #26 from DanielWright/master

Bump to 9.3.1