Exclude auto-snapshot versions

Fedora4 creates snapshot versions prior to restoring previous versions.
We don’t want to count these as part of our versions.
Merge pull request #619 from projecthydra/snapshot-versions

Exclude auto-snapshot versions
Preparing for 9.0.0.beta2 release
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