Removing network manager / refactoring metadata manager to use RestRequest and RestClient

Also new rest wrappers for search scope and order / search result layout
Tests for new wrappers
I don't think we need this setter. Since each instance of ```MetadataManager``` is linked to a specific ```UserAccount```, if we use ```clientManager.peekRestClient(userAccount)``` in the constructor, we should always have the right ```RestClient``` instance. Exposing this setter could cause mismatches.