IPVS: netns awareness to ip_vs_est

All variables moved to struct ipvs,
most external changes fixed (i.e. init_net removed)

*v3
 timer per ns instead of a common timer in estimator.

Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>