Two constants: MAX_CHAIN_LEN_{WRAP,NOWRAP} are now moved
to common.constants file and renamed to
MAX_IPTABLES_CHAIN_LEN_{WRAP,NOWRAP}.
It is done because at least one of them might be now used
outside iptables_manager module (in port_forwarding
extensions)
Change-Id: I9b7a24b0264631e74b3c05b73a22a6a9c2752e82