Register multiple output. TaskChain for tree of requests

Further improvement to the existing taskchain dictionnary generation to extend it to a tree of requests like:

https://cms-pdmv-dev.cern.ch/mcm/chained_requests?root_request=SUS-Fall13wmLHE-00011

 already tested against request manager testbed with success using an exterior test setup.

In case of a workflow with multiple outputs like taskchain workflow, the single request inspection will pick up the proper clones and the proper statistics of the proper output datasets.

This could go in -int at some dedicated point to be able to trigger the inspection of real workflow getting to completion.
Exercising in -dev will require more manipulations.