Upgrade ignore dependency

[futpib]

fixes #92

[sindresorhus]

Can you describe the changes? Also see #104 for a previous attempt that I don't think is correct.

[futpib]

After upgrade you get invalid path errors you showed in #92 (comment). The ignore upgrade guide says they made paths starting with ./ or ../ invalid. I saw that these were introduced by path.relative call in ignores.ignores(slash(path.relative(cwd, p))) and changed it to ignores.ignores(slash(p)). At this point I trusted green tests and submitted the PR.

Now, after a closer look, I see that this almost made sense except for a call like globby.sync('../foo/*', { gitignore: true } and a .gitignore file in cwd, which is not covered by the tests, which would result in ignores call with a path starting with ../.

I might come back to this with a better PR.