Autofocus username.

guacamole/src/main/webapp/index.xhtml

@@ -43,7 +43,7 @@
                             <table>
                                 <tr>
                                     <th>Username</th>
-                                    <td><input type="text" name="username" id="username"/></td>
+                                    <td><input type="text" name="username" id="username" autofocus="autofocus"/></td>
                                 </tr>
                                 <tr>
                                     <th>Password</th>