Change default database to postgresql for all environments.

Added and installed `pg' gem. Re-ran database migrations for pg.
Updated database.yml to work with pg; credentials are stored in
application.yml.
Change default database to postgresql for all environments.

Added and installed `pg' gem. Re-ran database migrations for pg.
Updated database.yml to work with pg; credentials are stored in
application.yml.
Merge branch 'master' of github.com:dvdhsu/hughsball

Force pull because amended commit on previous push.
Fix merge conflict on database.yml