v0.0.6

• Added --ssh-image flag to allow specifying custom OpenSSH image as requested in #20
• Bump OpenSSH image (added ./hack/build-sshd-image.sh)

555d50d5bed601c2e91f7444b3f44fdc424d721d7da72955725a97f3860e2517  ./kwt-darwin-amd64
92a1f18be6a8dca15b7537f4cc666713b556630c20c9246b335931a9379196a0  ./kwt-linux-amd64

(Installation instructions: https://k14s.io/#install-from-github-release)