Added unit test for helpers.massSearchReplaceAnyInputTag()
Remove unnecessary object copying in helpers.MassSearchReplaceAnyInputTagVisitor()

According to help(cms.PSet) parameters_() copies all the contained
parameter objects, while in this case it is enough to iterate over the
names.
Merge pull request #727 from makortel/pathelpers

Performance improvement in PAT helpers.py (70X)