Update jquery.multiselect.filter.js

Set filter plugin compatabile fo Jquery 2.0
Issue #434

Author: Andrey

src/jquery.multiselect.filter.js

@@ -30,7 +30,7 @@
       var elem = $(this.element);
 
       // get the multiselect instance
-      var instance = (this.instance = (elem.data('echMultiselect') || elem.data("multiselect")));
+      var instance = (this.instance = (elem.data('echMultiselect') || elem.data("multiselect") || elem.data("ech-multiselect")));
 
       // store header; add filter class so the close/check all/uncheck all links can be positioned correctly
       var header = (this.header = instance.menu.find('.ui-multiselect-header').addClass('ui-multiselect-hasfilter'));