Make Hydra::Datastream::RightsMetadata#to_solr use Hydra config to get Solr field names.
Make Hydra::Datastream::InheritableRightsMetadata#to_solr use Hydra config to get Solr field names.
Added permissions and inherited permissions field names to stub Hydra config in hydra-access-controls spec_helper.
Merge pull request #125 from dchandekstark/rights-md-to-solr-use-config

Make Hydra::Datastream::RightsMetadata#to_solr use Hydra config to get Solr field names.