Should not add unrelated files in commit.

[PeterDaveHello]

I found that if there are some untracked files in the repo, cdnjs-importer will add them all with the commit, we should only add the files been fetched by the importer, not them all.

[petrgazarov]

This might be why: https://github.com/cdnjs/cdnjs-importer/blob/master/lib/index.js#L275
Might be better to use something along the lines of

self.git.exec(OArgv({
  _: package.name
  , b: true
}, "add"), cb)