Dockerfiles are built with _tagged_ commits
Dockerfiles are built with _tagged_ commits

If the commit is tagged, then the release is solid, and we can build our
Dockerfiles.

Previously the Dockerfiles were built with every change. Now that I'm
making Dockerfiles first-class citizens ("Official Docker Images"), we
need discipline when building them.

[#21]

cunnie/sslip.io,cunnie/sslip.io,cunnie/sslip.io,cunnie/sslip.io