Publish Python package to conda-forge

Having the `openlocationcode` package available through [conda-forge](https://conda-forge.org/index.html#about) as well as PyPi would be a big help as it would allow developers to use it as a dependency in other conda-forge packages (see davemlz/eemont#23). [Adding it to conda-forge](https://conda-forge.org/docs/maintainer/adding_pkgs.html) should be pretty straightforward since OLC has no dependencies.

Thanks!