Cleanup builtins db initialization

Instead of doing the initialization in Catalog.java, there is now a special
BuiltinsDb that handles this initialization. This makes in more clear what file
should be modified when adding a new builtin and also cuts down the code in the Catalog.

Change-Id: I4512abff6e8c7f4924701aeffe10e656104a0b86
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2567
Reviewed-by: Lenni Kuff <lskuff@cloudera.com>
Tested-by: jenkins