Rename all leading _ files

[insin]

Would it be possible to extend renaming of _ prefixed files to include all files with the prefix, not just dotfiles?

I just discovered that npm will read nested package.json files in your project, which caused this packaging issue with some templates I was providing: insin/nwb#21

To avoid this, I would need to rename package.json files which will be copied by copy-template-dir to _package.json.

I can create a PR for this later if you're ok with the proposed change.

[yoshuawuyts]

I'd be happy to get a PR for this in.

[yoshuawuyts]

Released as v1.1.0.