Initialize API
New backend engine - Redis

Version 0.2
Adding a Unit Test
Small API fixes:

_serialize and _unserialize methods
Update README.md
README.md - update API
README.md - update EVENTS section
README.md - update ENGINES section
Update README.md
Update README.md
Adding a Method to the Cache API

* hasKey
Small API fixes

- memory engine: hasKey
Redis engine
Merge branch 'development'