Disallowing DROP DATABASE via privileges

At the moment, there is no separation between DROP TABLE and DROP DATABASE.

There is a mysql bug from 2006 that captures this enhancement request: http://bugs.mysql.com/bug.php?id=18938

Similar to this bug report, in our use case, the DATABASE schemas are automatically created by our software. While multiple users may create and remove tables within that database, we would prefer to prevent them from dropping the entire database without using the Cloud Foundry mechanisms that were used to provision the database in the first place.

Without this restriction, we've had to make various parts of our software smarter, to not automatically assume that a database we've created always exists until our software has deleted it.