Mark Hetherington

Adds a GCS metadata name space that returns GCS specific data.

If the root_path has a trailing slash, fix_storage will encounter an infinite loop. To prevent this, we prohibit the root_path having a trailing slash. Closes #55

Within [_gcsfs.py in the fix_storage process](https://github.com/Othoz/gcsfs/blob/c219b9ceb7b1671a53f2ebded4e8eb47f6f0b4d8/fs_gcsfs/_gcsfs.py#L494) if the root_path ends with a slash, there is an infinite loop. This is because the dirname function will return each parent directory without...