Hublo integration

Hi,

Here is a pull to add Hublo (https://www.hublo.com).

Actually had to fiddle a bit to make tests pass (see https://github.com/hublo/analytics.js-integrations/commit/778f9a0eb7ae4b194a3d6160122e39e94b8e4084, that I didn't include in the pull).
I suspect I wasn't supposed to, so I didn't put it in the pull, but I'll be happy to make any necessary changes.

I fail to attach the `.eps` logo within the pull ("unsupported file type"), sending it over email.

Thanks,

Léo