add macvlan vepa and bridge mode

add macvlan vepa and bridge mode

The future kernel 2.6.33 will incorporate the macvlan bridge
mode where all the macvlan will be able to communicate if they are
using the same physical interface. This is an interesting feature
to have containers to communicate together. If we are outside of the
container, we have to setup a macvlan on the same physical interface than
the containers and use it to communicate with them.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>