Updated feed transformer files to place empty strings for variables when JSON path finds an empty element; added an if check to no create a link for an empty subject link or attachment file id element.
Merge pull request #3 from JohnWMay/master

Updated feed transformer files to place empty strings for variables when...
Updated entryId code to use docIdStr parameter value if not doc id found
Merge pull request #4 from JohnWMay/master

Updated entryId code to use docIdStr parameter value if not doc id found