More SDK cleanup.

- Renamed description property on AlfrescoPerson to summary
- Moved person profile constants to internal constants file as they only appear to be used internally
- Removed (unused) clearFavoritesCache method method from public AlfrescoDocumentFolderService interface (all services will get a clear method in the future)
clearFavoritesCache is actually called by the app, added it back as "clear", which will be added for all services in the future.