dashboard: some help message for save resource

circle/dashboard/static/dashboard/vm-details.js

@@ -370,8 +370,10 @@ function checkNewActivity(only_status, runs) {
 
       if(data['status'] == "STOPPED") {
         $(".enabled-when-stopped").prop("disabled", false);
+        $(".hide-when-stopped").hide();
       } else {
         $(".enabled-when-stopped").prop("disabled", true);
+        $(".hide-when-stopped").show();
       }
 
       if(runs > 0 && decideActivityRefresh()) {

circle/dashboard/templates/dashboard/vm-detail/resources.html

@@ -41,6 +41,9 @@
       {% if not op.resources_change %}disabled{% endif %}>
       <i class="icon-save"></i> {% trans "Save resources" %}
     </button>
+    <span class="hide-when-stopped"
+      {% if op.resources_change %}style="display: none;"{% endif %}
+      >{% trans "Stop your VM to change resources." %}</span>
   </div>
 </p>
 {% endif %}