add support for polling specific definition file.
this splits the existing polling specific options out of
pipeline.yaml as transformations only exists on notifcation agent
and polling interval/discovery only exists on polling agents.
backward compatibility is maintained so pipeline.yaml file from
previous releases can still be passed in as polling definition file.
Change-Id: I206566349f98d6b17336cd5ea36ceb1e304dd90c
8999528092