Hardening/619 forbidden characters

### Description
o The response to 'Service not found: $URL' changed to 'unrecognized request', to avoid to respond with the data that the user supplied (security risk)
o Requests with any of the 'forbidden characters' in the values of the payload (see issue #619) are refused, both for XML and JSON.

You mean that we are fixing a bug *previously existing* before this PR? Or a bug "caused inside" the PR itself?

In the first case, I think it worths a comment on the CHANGEX_NEXT_RELEASE file.