Makes run-cosmos request a fleetlock lock before running cosmos "update"
and "apply" steps. This is helpful for making sure only one (or several)
machine out of some set of machines runs cosmos changes at a time. This
way if cosmos (or puppet) decides that a service needs to be restarted
this will only happen on a subset of machines at a time. When the cosmos
"apply" is done a fleetlock unlock request will be performed so the
other machines can progress.
The unlock code in run-cosmos will also run the new tool
sunet-machine-healthy to decide things are good before unlocking. This
way if a restarted service breaks this will stop the unlock attempt
and in turn make it so the others should not break their service as
well, giving an operator time to figure out what is wrong.
