Reset auth cookie before re-auth in login page.

git-svn-id: http://svn.us.apache.org/repos/asf/tuscany@1041680 13f79535-47bb-0310-9956-ffa450edef68

sca-cpp/trunk/modules/http/htdocs/login/index.html

@@ -21,6 +21,7 @@
 
 <script type="text/javascript">
 function submitFormSignin() {
+    document.cookie = 'TuscanyOpenAuth=;expires=' + new Date(1970,01,01).toGMTString() + ';path=/;secure=TRUE';
     document.formSignin.httpd_location.value = '/';
     document.formSignin.submit();
 }