TODO: Remove "OpenFlow Group Bucket Stats" from TODO list

Signed-off-by: Ryan Wilson <wryan@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
FAQ: Add a list of upstream kernel version supporting tunneling.

Reported-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>