make dropdowns toggle when clicked (for mobile)

js/bootstrap-dropdown.js

@@ -38,12 +38,14 @@
       var $this = $(this)
         , selector = $this.attr('data-target') || $this.attr('href')
         , $parent = $(selector)
+        , isActive
 
       $parent.length || ($parent = $this.parent())
+      isActive = $parent.hasClass('open')
 
       clearMenus()
 
-      !$parent.hasClass('open') && $parent.toggleClass('open')
+      !isActive && $parent.toggleClass('open')
 
       return false
     }