Change installer to use postgres.

Note that more changes are likely needed to get installer back to fully working
using postgres.
Fix typo in ceilometer notifier constraint name
Merge pull request #402 from bcrochet/ceilo-constraint-fix

Fix typo in ceilometer notifier constraint name
Use account security from mysql puppet to remove defaults
Merge pull request #403 from bcrochet/galera-acct-security

Use account security from mysql puppet to remove defaults