network: Rely on netlink handler to improve performance
network: Rely on netlink handler to improve performance

Instead of opening/closing the netlink socket everytime we need
to perform a netlink action, we rely on a netlink handler which
keeps the socket opened until we decide to close it.

Signed-off-by: Sebastien Boeuf <90b401417360b1924ef3f520ddee932686110f85@intel.com>

clearcontainers/agent,clearcontainers/agent