add ssh support

[Oah433]

Can you please add ssh support to the image?
currently it shows "ssh: connect to host 172.17.0.2 port 22: Connection refused when trying to ssh to the container" and when running:
"sudo docker exec -it nginx-modsecurity /bin/bash" it showns:
"OCI runtime exec failed: exec failed: container_linux.go:349: starting container process caused "exec: "/bin/bash": stat /bin/bash: no such file or directory": unknown
"

[EvgenyPrikhodko]

sudo docker exec -it nginx-modsecurity sh