Pattern **/ matches everything

Hi.

Using glob version 0.3.0.

The pattern **/ should match all folders recursively. However it seems to also match files. Not sure if this is as intended, however in bash **/ works for matching folders only.
My test (fails on path3):

#[test]
pub fn test_pattern_recursive_dirs() {
        let path1 = Path::new("folder/");
        let path2 = Path::new("folder/folder/");
        let path3 = Path::new("folder/folder/file");
        let pattern = Pattern::new("**/").unwrap();
        assert!(pattern.matches_path(path1));
        assert!(pattern.matches_path(path2));
        assert!(!pattern.matches_path(path3));
}

If this is something to be fixed, I can look into it.

Start with the provided test_pattern_recursive_dirs test and the Pattern::new and Pattern::matches_path entry points. Reproduce the behavior for the **/ pattern, then trace how directory and file paths are distinguished. Done means the folder assertions pass and the file assertion for folder/folder/file remains false.