Add configurable opts for Line chart

Closes #1

LGTM given by: @scottmatthewman

Squashed commit of the following:

commit 85cddebfe17c77af756a72a70c2c7c025b3e692a
Author: Tonmoy Saikia <tonmoy.saikia@talentica.com>
Date:   Tue Jun 17 18:17:08 2014 +0530

    Add configurable opts for Line chart