CollectionAssociation#load_from_solr accepts a hash of options to pass through to ActiveFedora::SolrService.query,
and by default sets the :rows option to CollectionAssociation#count -- i.e., to return all results.
In order to stay "safe" CollectionAssociation#find_target explicitly passes :rows=>1000, which retains the current
behavior.  However, now when the assocation reader is called with :response_format=>:solr (and w/o :rows), all the results will be returned.  This permits the following:

   ActiveFedora::SolrService.lazy_reify_solr_results(association(response_format: :solr))

so that code can lazily iterate over all the target objects.
Merge pull request #300 from dchandekstark/load-from-solr-options

Add hash options to CollectionAssociation#load_from_solr