Create root schema without the "metadata" schema 

Root schema returned by ```Frameworks.createRootSchema``` contains ```metadata``` subschema. For some clients ```metadata``` schema is not needed. For example in Drill metadata is managed by INFORMATION_SCHEMA which is added as subschema to root schema.

Is it a good idea to pass a flag to ```Frameworks.createRootSchema``` to indicate whether ```metadata``` schema is expected or not in root schema?