VRFS-2701 remove error message when username is blank

web/app/assets/javascripts/site_validator.js.coffee

@@ -55,6 +55,8 @@ context.JK.SiteValidator = class SiteValidator
 
   validateSite: () =>
     unless data = this.dataToValidate()
+      if @success_callback
+        @success_callback(@input_div)
       return null
     this.setSiteStatus(null)
     @spinner.show()