- Added JSON schema for XACML Policy in (Authzforce custom) JSON format

- Fixed issues in Request/Response JSON schema
- Added XSLT stylesheets for XACML/XML to XACML/JSON (non-standard)
Policy(Set) conversion (see README.md for more info),
- Added Ant generation script and unit tests for testing validation with
the new Policy JSON schema and for testing those stylesheets XACML
conformance tests for testing two-way conversion (XML->JSON->XML)
- Improved XacmlJsonUtils#canonicalizeResponse(...) to ignore
IncludeInResult in Response's Attributes comparison
- Updated license headers for year 2020