app/rest_firewall: add API for VLAN configuration

add REST-API for VLAN configuration of rest_firewall application.
it implements handling each vlan groups separately.

This update(v1->v2) contains the following change. make function of
 conversion of cookie and ruleID for easily understanding.

Signed-off-by: WATANABE Fumitaka <watanabe.fumitaka@nttcom.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>