Support session locking
Close connection on class destruction

Conflicts:
	Client/Phpredis/Client.php
Check if connection exist before closing connection
Support session locking
Added session locking support
Fixed a bug, locking the wrong key
modified former session tests to use non locking session
added a test to verify session locking
fixed coding style typo
Merge pull request #120 from shtouff/session-locking

Session locking