Add J3.3.0 password verification compatibility

When sharing users between different joomla version, the password can be modified by joomla 3.3 that forbid joomla 2.5 to login.
Add this verification when PHP 5.3.10 is available, this make the compatibility available with J3.3

This change require to add the J3.3 /libraries/compat directory included in J2.5.20