RVRNEXT-30 fix submit button name

public/static/js/rvr.js

@@ -196,7 +196,7 @@ var RVR = {
             }
         }
 
-        form.elements.submit.disabled = !anyChanged;
+        form.elements['submit_button'].disabled = !anyChanged;
     },
 
     observeInputsInForm: function (form, observedInputs) {
@@ -219,7 +219,7 @@ var RVR = {
         }
 
         form.onreset = function () {
-            form.elements.submit.disabled = true;
+            form.elements['submit_button'].disabled = true;
         }
     },