#56 refactor

[Carlos Gacimartín]

Refactoring, extract some repeated pieces of code into a library. I.e:

function beforeFilter() {
$groupid = $this->Session->read('group');
$polid = $this->Session->read('pol');
$solid = $this->Session->read('sol');
if (!$groupid || !$polid || !$solid) {
$this->redirect('/users/login');
}
}