Fixing subworkflow resolution algorithm

* Made necessary changes to be able to use short workflow names in DSL
  if they are defined within the same workbook as a calling workflow.
  The algorithm first tries to find a workflow assuming it's in the
  same workbook and if it doesn't exist then uses its name defined
  in DSL as a global name to find the workflow DB instance without
  prefixing it.

Change-Id: Id118cd89ebf290e49210a1699d422587b73c9d1f