Fix Idempotency of Database Handling

1. 'reset_db' was doing too much on its own. Delegated to Rails' built
   in Rake tasks
2. Non-reset case updated to attempt to create DB (always safe), and to
   update test DB if need be

Resolves #15
Merge pull request #16 from jherdman/15-idempotent-database-script

Fix Idempotency of Database Handling