disable run simulation button when simulation is already running

dream/platform/static/index.html

@@ -11,6 +11,7 @@
   <link rel="stylesheet" type="text/css" href="css/jquery.handsontable.full.css">
   <link rel="stylesheet" type="text/css" href="lib/dhtmlxgantt/dhtmlxgantt.css">
   <link rel="stylesheet" href="css/demo-new.css">
+  <link rel="stylesheet" href="css/font-awesome.css">
 
 </head>
 
@@ -56,7 +57,9 @@
           <form>
             <fieldset id="general-fieldset">
             </fieldset>
-            <a id="run_simulation">Run Simulation</a>
+            <a id="run_simulation">
+            <i class="fa fa-spinner fa-spin" id="loading_spinner" style="display:none"></i> 
+              Run Simulation</a>
           </form>
         </div>
       </div>

dream/platform/static/src/dream_launcher.js

@@ -138,12 +138,15 @@
     });
 
 
-
     // Enable "Run Simulation" button
     $("#run_simulation").button().click(
       function (e) {
+        $("#loading_spinner").show();
+        $("#run_simulation").button('disable');
         dream_instance.runSimulation(
           function (data) {
+            $("#loading_spinner").hide();
+            $("#run_simulation").button('enable');
             $('#result_list').empty();
             if (data['success']) {
               $("#json_result").val(JSON.stringify(data['success'],