Get network stats through netlink rather than from /proc

This add a dependency to the netlink opam package, and the libnl-3
and libnl-route-3 libraries.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
Update oasis

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
Merge pull request #32 from robhoes/ea1254

Get network stats through netlink rather than from /proc