enable 'save' buttons on form changes

hobo/environment/templates/environment/home.html

@@ -46,7 +46,7 @@
   <p>
   <form class="small">
     {{ service|as_update_form }}
-    <button disabled="disabled">{% trans 'Save' %}</button>
+    <button class="enable-on-change" disabled="disabled">{% trans 'Save' %}</button>
   </form>
   </div>
   {% endfor %}
@@ -87,6 +87,12 @@ $(function() {
   $("div[data-wants-check='true']").each(function(index, element) {
     $(element).operational_check();
   });
+
+  $('button.enable-on-change').each(function(index, element) {
+    var button = $(element);
+    $(element).parent('form').find('input').on('change keydown',
+            function() { $(button).prop('disabled', null); });
+  });
 });
 </script>
 {% endblock %}