Ensure $SIP also effects docker_public_host
Ensure $SIP also effects docker_public_host

Previously, would only apply to shell_hostname, which causes issues during
installation of sample problems.

picoCTF/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF