Add "SecurityOptions" in Info.
Add "SecurityOptions" in Info.

This PR tries to add SecurityOptions field in Info so that
security options such as apparmor, seccomp, or selinux could
be displayed by `docker info`.

Detailed discussion could be found in:
https://github.com/docker/docker/issues/20909
https://github.com/docker/docker/pull/21172

Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>

vdemeester/engine-api,docker/engine-api,mikedougherty/engine-api,thaJeztah/engine-api,jwhonce/engine-api