Remove double call to initializeCas
Remove double call to initializeCas

Because initializeCas() is a part of the constructor, it is guaranteed to have run before the logout function.  I use Laravel sessions so I kill the local CAS session immediately after login, but unless the user specifically requests a logout, I don't kill the session at the server.  (Thus, I always call logout with no current authenticated user.)  Currently this results in a PHP error: ``phpCAS error: phpCAS::client(): phpCAS::client() has already been called (at /home/vagrant/Code/mysbts/vendor/xavrsl/cas/src/Xavrsl/Cas/Sso.php:76) in /home/vagrant/Code/mysbts/vendor/xavrsl/cas/src/Xavrsl/Cas/Sso.php on line 76`` because initializeCas has been called twice and wich calls $this->configureCasClient(); twice which calls phpCAS::client() twice.
XavRsl/Cas,liyunde/laravel5-multi-cas,samyerkes/Cas