host: Add ActiveJob.HostID

Signed-off-by: Lewis Marshall <lewis@lmars.net>
controller: Move parseJobID into cluster package

Signed-off-by: Lewis Marshall <lewis@lmars.net>
host/cli: Manage jobs across the cluster

Signed-off-by: Lewis Marshall <lewis@lmars.net>
Merge pull request #254 from flynn/flynn-host-cli-cluster

host/cli: Manage jobs across the cluster