Put hidden d2c-button dev behind waffle flag.

apps/addons/templates/addons/impala/button.html

@@ -70,15 +70,17 @@
   {% endif %}
 {% endif %}
 
-{% with reasons=version.is_compatible[1] %}
-  <div class="d2c-reasons-popup popup">
-    <p>{% trans app=APP.pretty %}
-      This add-on is not compatible with your version of {{ app }} because of
-      the following:
-    {% endtrans %}</p>
-    <ul>{% for reason in reasons %}<li>{{ reason }}</li>{% endfor %}</ul>
-  </div>
-{% endwith %}
+{% if waffle.switch('d2c-buttons') %}
+  {% with reasons=version.is_compatible[1] %}
+    <div class="d2c-reasons-popup popup">
+      <p>{% trans app=APP.pretty %}
+        This add-on is not compatible with your version of {{ app }} because of
+        the following:
+      {% endtrans %}</p>
+      <ul>{% for reason in reasons %}<li>{{ reason }}</li>{% endfor %}</ul>
+    </div>
+  {% endwith %}
+{% endif %}
 
 </div> {# install-shell #}