yet another map ordering test bug

[Dave Cheney]

FAIL: run_test.go:269: RunSuite.TestAllMachines

run_test.go:293:
    c.Check(testing.Stdout(context), gc.Equals, string(jsonFormatted)+"\n")
... obtained string = "[{\"Error\":\"command timed out\",\"MachineId\":\"1\",\"Stdout\":\"\"},{\"MachineId\":\"0\",\"Stdout\":\"megatron\\n\"}]\n"
... expected string = "[{\"MachineId\":\"0\",\"Stdout\":\"megatron\\n\"},{\"Error\":\"command timed out\",\"MachineId\":\"1\",\"Stdout\":\"\"}]\n"

OOPS: 233 passed, 1 FAILED
--- FAIL: TestPackage (155.82 seconds)
FAIL
FAIL github.com/juju/juju/cmd/juju 155.991s