Refactor the lookup of solr fields for a predicate
Now all of the mapping from predicate to solr_field is consolidated in the
Reflection. Previously this logic was in two different places.
Extract query building and result processing from SolrService
Don't use predicate uri as a solr key, colins and slashes are not supported
Merge pull request #611 from projecthydra/refactor_solr_keys

Refactor lookup of solr fields Fixes #605