Merge branch 'reduce-elementadmin-queries' into 'master'

Reduce number of queries in Element Admin

Closes #587

See merge request !1245

arkindex/documents/admin.py

@@ -37,7 +37,7 @@ class CorpusAdmin(admin.ModelAdmin):
 class ClassificationInline(admin.TabularInline):
     model = Classification
     readonly_fields = ('confidence', 'high_confidence', )
-    raw_id_fields = ('worker_version', )
+    raw_id_fields = ('worker_version', 'moderator', 'ml_class')
 
 
 class AllowedMetaDataAdmin(admin.ModelAdmin):