Terminating a framework during master failover leads to orphaned tasks

Repro steps:

1) Setup:

bin/mesos-master.sh --work_dir=/tmp/master
bin/mesos-slave.sh --work_dir=/tmp/slave --master=localhost:5050
src/mesos-execute --checkpoint --command="sleep 1000" --master=localhost:5050 --name="test"

2) Kill all three from (1), in the order they were started.

3) Restart the master and agent. Do not restart the framework.

Result)

• The agent will reconnect to an orphaned task.
• The Web UI will report no memory usage
• curl localhost:5050/metrics/snapshot will say: "master/mem_used": 128,

Cause)
When a framework registers with the master, it provides a failover_timeout, in case the framework disconnects. If the framework disconnects and does not reconnect within this failover_timeout, the master will kill all tasks belonging to the framework.

However, the master does not persist this failover_timeout across master failover. The master will "forget" about a framework if:
1) The master dies before failover_timeout passes.
2) The framework dies while the master is dead.

When the master comes back up, the agent will re-register. The agent will report the orphaned task(s). Because the master failed over, it does not know these tasks are orphans (i.e. it thinks the frameworks might re-register).

Proposed solution)
The master should save the FrameworkID and failover_timeout in the registry. Upon recovery, the master should resume the failover_timeout timers.