restore load_instance_from_solr to the fedora-4 branch

[jcoyne]

$ git grep -n load_instance_from_solr app/ sufia-models
app/controllers/concerns/sufia/batch_edits_controller_behavior.rb:26:          gf = ::GenericFile.load_instance_from_solr(doc_id)
app/controllers/concerns/sufia/transfers_controller_behavior.rb:22:      @generic_file = ::GenericFile.load_instance_from_solr(@pid)
app/controllers/concerns/sufia/transfers_controller_behavior.rb:62:      raise Hydra::AccessDenied unless ::GenericFile.load_instance_from_solr(@pid).de
app/controllers/single_use_links_controller.rb:45:    @asset = ActiveFedora::Base.load_instance_from_solr(params[:id])
app/controllers/single_use_links_viewer_controller.rb:64:    @asset = ActiveFedora::Base.load_instance_from_solr(single_use_link.itemId)
app/models/concerns/sufia/solr_document_behavior.rb:33:      m = ActiveFedora::Base.load_instance_from_solr(id, self)
app/views/collections/_show_document_list_row.html.erb:3:  <% gf = GenericFile.load_instance_from_solr(document.id) %>
app/views/my/_index_partials/_list_files.html.erb:3:  <% gf = GenericFile.load_instance_from_solr(document.id) %>
sufia-models/app/models/checksum_audit_log.rb:13:    logs = GenericFile.load_instance_from_solr(version.pid).logs(version.dsid)
sufia-models/app/models/concerns/sufia/ability.rb:51:      ::GenericFile.load_instance_from_solr(pid).depositor
sufia-models/app/models/concerns/sufia/user.rb:58:      ::GenericFile.load_instance_from_solr(Sufia::Noid.namespaceize(t.generic_file_id))
111

[jcoyne]

This may speed things up a bit