CAS-1371: Fixed a bug where requiring to create sessions at the JSP layer gums up the next login attempt from that browser session within the servlet session duration.  This can be reproduced via:

1) log in to an application via CAS.
2) Log out from application, terminating application-local session and redirecting to cas/logout .  This terminates previous and issues new servlet session with corresponding JSESSIONID cookie.
3) without closing browser, try to log in to the application again via CAS.  This deposits you to the CAS login form, of course.
4) correctly complete and submit the CAS login form, but be rejected! CAS redirects back to and displays login form again, issuing a new JSESSIONID.
5) correctly complete and submit the CAS login form.
Merge branch 'CAS-1371' of github.com:Unicon/cas into CAS-1371