Fixes & Additions

+ Removed `system/session`

+ Removed Gleez namespace for Session classes

+ Small fix must help run Gleez in hiphop-php.
   Argument 2 passed to ArrayObject::__construct() must be an instance of int
   See http://php.net/manual/en/arrayobject.construct.php

+ Redesign Gravatar::download - For security reasons,
   removed the display destination for downloading the file when an
   exception occurs. Corrections in the logic of the algorithm

+ Updated Gravatar config

+ `Valid::in_range`, `Valid::range_length`

+ Updated Cerber Theme