added --persist option so that it tries to re-use existing solr index rather than downloading a fresh one, and also doesn't throw errors when existing solr index already has hydra-works core defined
added --persist option so that it tries to re-use existing solr index rather than downloading a fresh one, and also doesn't throw errors when existing solr index already has hydra-works core defined

digital-york/researchdatayork,digital-york/researchdatayork,digital-york/researchdatayork,digital-york/researchdatayork