Authorization url is hardcoded - doesn't account for other data centers

[macmartine]

https://github.com/HubspotCommunity/hubspot-ruby/blob/8eb0a64dd0c14c79e631e81bfdc169583e775a46/lib/hubspot/oauth.rb#LL25C30-L25C31

Yet when I log in to hubspot, I'm on : https://app-eu1.hubspot.com/