fixing unicode error

We are requiring all the prep/sample templates to be UTF8, however, our code was not working with UTF8, only with ascii. The only spot were I found the issue is in qiita_ware.util and the problem was that we were import `bytes` and `str` from `future.builtins`. I removed this import and everything works smoothly. The function that we were using `bytes` and `str` was extracted from `skbio`. Since we have updated our version, we can import now directly from there, and avoid code duplication and the issue on Qiita.

Should be fast to review!! Any takers??