Expose, honor "allow future" setting for vendor catalog batch

tailbone/templates/batch/vendorcatalog/configure.mako

@@ -3,6 +3,19 @@
 
 <%def name="form_content()">
   ${self.input_file_templates_section()}
+
+  <h3 class="block is-size-3">Options</h3>
+  <div class="block" style="padding-left: 2rem;">
+
+    <b-field>
+      <b-checkbox name="rattail.batch.vendor_catalog.allow_future"
+                  v-model="simpleSettings['rattail.batch.vendor_catalog.allow_future']"
+                  @input="settingsNeedSaved = true">
+        Allow "future" cost changes
+      </b-checkbox>
+    </b-field>
+
+  </div>
 </%def>