implement LdpToOaMapper.map_specific_resource
first integration test for SpecificResource passes; fixes to method in LdpToOaMapper as needed
implement SpecificResource for bodies in LdpCreator; integration spec written for FragmentSelector body
add test for addl param added to LdpCreator.map_external_ref
comment out some pending specs we have no intention of implementing
finished integration tests for SpecificResource in targets and bodies