Path Exclusion Pattern

[ThomasBrierley]

It is useful to exclude some files from being copied to the content server without having to exclude them from deploy trees in the git repo. For this purpose a configurable exclusion pattern can be used to filter out files in the sync stage. e.g underscore prefixes (_name) are a common pattern used to exclude files from build systems in web development.

This belongs in the .pegit.json config file, and the interactive config generator should be extended appropriately to match.