added a config option for the underscores

I didn't see a point of converting _'s to .'s

I set it so you can enable a config option to have this option but it
should be off by default since I know a lot of people and apps that use
the underscore in database names.
Merge pull request #233 from mzupan/postgresql

added a config option for the underscores
Merge branch 'master' of github.com:BrightcoveOS/Diamond