Merge branch 'improve-workerversion-admin' into 'master'

Set docker_image and revision as raw ID fields in WorkerVersion admin

Closes #956

See merge request !1631

arkindex/dataimport/admin.py

@@ -110,6 +110,7 @@ class WorkerVersionAdmin(admin.ModelAdmin):
     list_filter = ('worker', )
     field = ('id', 'worker', 'revision', 'configuration')
     readonly_fields = ('id', )
+    raw_id_fields = ('docker_image', 'revision')
 
 
 class WorkerConfigurationAdmin(admin.ModelAdmin):