Don't require redis if a client is passed

Signed-off-by: Loïc Mahieu <mahieuloic@gmail.com>
Possibility to pass logger in option

Signed-off-by: Loïc Mahieu <mahieuloic@gmail.com>
better config

Signed-off-by: Loïc Mahieu <mahieuloic@gmail.com>
release 0.2.0