re-factoring
* moving certain data types to correct services' data type projects: fosters service separation
* moving tags, discs and overall rating properties of entity description data types to super description class SSEntityDescA
* moving jsonld descriptions of entity description data types to super description class SSEntityDescA
* re-factored op entitySearchWithTagWithin on server-side to entitySearchWithKeywordWithin, hence it can be used for not only tag searches
Merge branch 'master' of https://github.com/learning-layers/SocialSemanticServer