analytics user and grants for core db tasks

This updates our core database rake tasks to:
 1. Pull down the `analytics_grants` schema from API in order
 2. Drop and create an analytics user with password `password` (for testing)

This will allow us to test connections against the read-only analytics user and its grants in our unit tests to poke out problems that we might have in the future when using analytics as our main gateway to the core database.