test: measure the time taken by 10 sequential connections
test: measure the time taken by 10 sequential connections

On my MBP I can do 1000 in 0.32s; doing 10 is very fast. This test
fails if 10 connections takes more than 1s, which could happen if there
was a 100-200ms delay somewhere in the path.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@docker.com>

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit