added DateTime behavior + tests
added README.md for Filter namespace , refs #170
fixed headline
fixed headline in readme
added filter component to main README.md , refs #170
added ORM Behaviors to main README.md contributions index , refs #179
added Upload\FileSize validator + tests
added Upload\MimeType validator + tests
fixed pager docs + added getPagesInRange method for easier pager usage without layout class + tests
fixed incorrect namespacing of PagerTest
Update README.md
Session Dostroy compatible with Phalcon 1.3

From Phalcon 1.3 Phalcon\Session\AdapterInterface is compatible with SessionHandlerIterface so to works with 1.3.0 destroy method must have parameter $session_id
Fix memcache destory for Phalcon 1.3.0
Update Mongo:destroy() for Phalcon 1.3.0
Uses type hinting
Documentation fixes
Improve MongoDB Session Adapter

- improve performance: prevent multiple findOne() on read() and write()
- improve performance: do not write, if session data did not change
- improve performance: use session_id() as _id to use index
- implement garbage collection
- fix doc block
- streamline variable names
Implement \SessionHandlerInterface
Do not implement \SessionHandlerInterface to keep compatibility with PHP 5.3
Twig: fix getSecurityToken/TokenKey not working

php error is: Using $this when not in object context in <b>/[..]/app/incubator/Mvc/View/Engine/Twig.php</b>