ensure that distributed_shampoo.utils is installed (#26)

Summary:
the utils module isn't available after pip install-ing, so much of the reference examples simply fail with an import error

Pull Request resolved: facebookresearch/optimizers#26

Reviewed By: anana10c

Differential Revision: D64189522

Pulled By: tsunghsienlee

fbshipit-source-id: b22285a11b8da5fe86ec6f7105ab52ac9834a52e