ACL based forwarding

ACL based forwarding

A poor man's flow switching or policy based rounting.

An ACL is used to match packets and is associated with a [set of] forwarding paths
that determine how to forward matched packets - collectively this association is a
'policy'.
Policies are then 'attached', in a priority order, to an interface when thaey are
encountered as an input feature. If a packet matches no policies it is forwarded
normally in the IP FIB.

This commit is used to test the "ACL-as-a-service" functionality,
which currently compiles, and the existing traffic ACL tests pass in both hash and linear modes.

Change-Id: I0b274ec9f2e645352fa898b43eb54c457e195964
Signed-off-by: Neale Ranns <nranns@cisco.com>
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Signed-off-by: Ole Troan <ot@cisco.com>