GUAC-324: Add functions for showing/hiding menu. Update menu title with connection name.

guacamole/src/main/webapp/client.xhtml

@@ -55,7 +55,7 @@
 
         <!-- Menu -->
         <div id="menu">
-            <h2>Guacamole ${project.version}</h2>
+            <h2 id="menu-title">Guacamole ${project.version}</h2>
             <div class="content">
                 <button>Test button</button>
                 <button>Test button</button>