Integrate 'Metadata Objects' table into 'Compose Service' form.

All actions in this table are still to be implemented (currently there
are stubs there).

Also some mechanism of value extraction from table should be
implemented (to actually select new files for a given service, as well
as add some files to a Service that doesn't exist yet).

Change-Id: Ia49edf186c22bbf443b51e70fb8cbac72e710e2a