Link dockerfile rules to upstream repo version of file with moban

[jayvdb]

The local version of the dockerfile rules is not linked to the upstream version of it.

This is quite a challenging problem, as the local version

• has modifications, such as removing of whitespace -- those could be submitted upstream, to avoid this problem
• is a template, because some parts of the file need to be excluded by downstream repos running moban

There are a few ways a moban template could link the upstream and local version, but the approach which feels the best is to have a 'template' which is of type 'patch', which would require a new moban plugin (moremoban/moban#75)