Credit goes to Idesman42 who has committed this patch in matter to blender.
Now you can set the Dof Object in the camera edit buttons - this patch makes it possible for camera to focus on an object rather then animating the Dof Dist IPO.
As this feature was asked by Blender users many times and Idesman42 is too modest to announce it loudly (it is hidden in less popular Python & Plugin forum) here is the link in matter:
https://projects.blender.org/tracker/index.php?func=detail&aid=7393&group_id=9&atid=127
http://blenderartists.org/forum/showthread.php?p=952019
Thank one more Idesman42 for this work 