responsive menu fix

responsive menu fix - data-target attribute added

src/main/webapp/WEB-INF/tags/menu.tag

@@ -8,14 +8,14 @@
     <div class="container">
         <div class="navbar-header">
             <a class="navbar-brand" href="<spring:url value="/" htmlEscape="true" />"><span></span></a>
-            <button type="button" class="navbar-toggle" data-toggle="collapse">
+            <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#main-navbar">
                 <span class="sr-only"><os-p>Toggle navigation</os-p></span>
                 <span class="icon-bar"></span>
                 <span class="icon-bar"></span>
                 <span class="icon-bar"></span>
             </button>
         </div>
-        <div class="navbar-collapse collapse">
+        <div class="navbar-collapse collapse" id="main-navbar">
             <ul class="nav navbar-nav navbar-right">
 
                 <petclinic:menuItem active="${name eq 'home'}" url="/" title="home page">