* Added abstraction for aggregation of granular permissions to support custom permissions.
* Refactor to move responsibility for aggregating granular permissions to the respective mappers.
* Added XML header comments for permission mappers.
* Tidied up/removed warnings in UserPresentationFactory interface and implementation.
* Optimized retrieval of documents in DocumentPermissionMapper.
* Fixed method header comment.
* Use entity service rather than content service to retrieve key and path.