DS-2168: New REST api with CRUD operations.

JIRA url: https://jira.duraspace.org/browse/DS-2168

New REST api with CRUD operations over community, collections, items, bitstreams. More information and description about changes in REST api are in description at JIRA task.
Actually, since this PR was created, metadata4all has been added, and Kevin seems to have added a fix the findAll(context, limit, offset) method for Oracle. I think it's safe to use that method now.