This change is an update to an earlier pull request to fix Issue
https://github.com/CocoaPods/CocoaPods/pull/572.

The earlier fix for clean paths is forcing some directories to lower
case which could cause some side effects. This fix removes the
`File::FNM_CASEFOLD` flag from the call to `Dir.glob` and allows the
OS to treat the directories as they wish. This makes the paths
returned in the `clean_paths` method consistent with those returned in
the `expanded_paths` method.

Podfile & Lockfile error handling

Closes 568.

Closes #519
Closes #568

Closes #570

Closes #244.

Closes #226

Closes #85

Closes #541

0.15.0