Add support for HubSpot Events API

[tuykin]

I need HubSpot Events API in my current project.
Did someone already implemented it? Or is there someone who need that API too?

[cbisnett]

PR #119 has some basic support for the Events API. I've requested a few changes and then I'll get it merged. From there we can add any of the other API endpoints you're looking for.

[fonji]

PR #208 replaces #119 and includes the requested changes