use __CLASS__ instead of get_called_class for php5.2 compatability
use __CLASS__ instead of get_called_class for php5.2 compatability

get_called_class, whilst alleviating the issue on 5.3 would result in different output to the previous code in situations where the class was extended. 

__CLASS__ returns the classname from the method's own class, ignoring inheritance, which matches existing behaviour.
MamunHoque/stripe-php,a-ankitpatel/stripe-php,stripe/stripe-php,matthewarkin/stripe-php,iFixit/stripe-php,5outh/stripe-php,Nayami/stripe-php