Add min diff threshold param when making price batch from product query

Hopefully this sets the stage for arbitrary batch params here..

tailbone/views/batch/pricing.py

@@ -43,13 +43,13 @@ class PricingBatchView(BatchMasterView):
     route_prefix = 'batch.pricing'
     url_prefix = '/batches/pricing'
     creatable = False
-    editable = False
     rows_editable = True
 
     def configure_fieldset(self, fs):
         fs.configure(
             include=[
                 fs.id,
+                fs.min_diff_threshold,
                 fs.created,
                 fs.created_by,
                 fs.executed,