Improve the error message when Hive URIs can't be loaded

The default error message when Hive URIs can't be loaded is to just say they can't be loaded. If you turn DEBUG logging on for the Registration class, you'll get a full stack trace which usually tells you the problem is the Hive JARs aren't on the classpath.

We should improve the default error message to tell users to confirm that the Hive JARs are in the classpath.