ofctl_rest: Fix security problems

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
rest_firewall: Fix security problems

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
rest_qos: Fix security problem

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
doc/app/ofctl_rest: Correct command examples

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>