Split cookbook into roles

:fork_and_knife: This splits the Supermarket cookbook into 3 roles: web, database and redis. In addition it allows you to configure Supermarket with an external database and redis server using the apps supermarket databag. By default supermarket will use localhost for both though if nothing is specified in the apps supermarket databag.

@cwebberOps This should take care of all three of those cards if you want to give this a review. You'll be able to now configure the database host, username, password and a redis url within the supermarket apps databag.