[Finishes #80559928] Resources API

    [#80559928] Tweaks to unit tests, chasing intermittent error in Travis for DataAccessManager not initialized
    [#80559928] Merged with fixes in develop and added a base class for API Tests
    [#80559928] Completed unit test for asset creation
    [#80559928] Added skeleton methods and API (routes) definition
    [#80559928] Added create (POST) API; refined and started to unify handling of common parts; the actual user is now associated with request, even if validation is disabled, if it exists