This changeset removes the shell wrapper the package used previously,
and uses the instance-management abilities of procd to track ssh
processes. Many fixes and improvements were integrated from the
package maintainer's branch at

https://github.com/nunojpg/packages/tree/sshtunnel

Signed-off-by: Kiril Zyapkov <kiril.zyapkov@gmail.com>

Signed-off-by: Nuno Goncalves <nunojpg@gmail.com>