Dereference/Enrichment/Media process fixes
Relative tickets:
- MET-1576 Fix Enrichment/Dereference issues
- MET-1593 Fix recognition of "grayscale" images in media library
Detailed changes:
- Proxy entity fields hasPart and isPartOf are not dereferenced anymore
- WebResource entity the hasPartList is not dereferenced anymore
- Added retries for "HttpServerErrorException" type exceptions on dereference and enrichment external calls
- Fixed the check from "grayscale" to checking "Gray" value during the setColorspace in WebResource of the
media library