LXC: gorouter_ctl.erb test for running in container is wrong

[justinsb]

https://github.com/cloudfoundry/cf-release/blob/master/jobs/gorouter/templates/gorouter_ctl.erb

tests for "running in container" (LXC) by doing this:

running_in_container() {
  grep -q '/instance' /proc/self/cgroup
}

However, for Juju, /proc/self/cgroup is /lxc.

Because this test is not correct, this means gorouter_ctl.erb on LXC tries to make some /proc/sys/net changes which are not supported on LXC, and thus gorouter fails to start.