Describe in detail the new feature you would like to see added

I'd like to be able to manage events guests, uninviting guests and messaging "Haven't Responded" users, etc. Just like I can do on the UI. 


Describe your use case, or some example use cases, for this feature

I use +events to provide training for my clients and solve their doubts. The issue is that a hangout have limited "seats", and although I invited a hundred people I'd like to "close" the event after the first 15 accepts. To prevent people from getting reserving their time to attend the meeting and getting frustrated for not being able to join the hangout because it's full.

The API would be very helpful because I would be able to quickly message and remove everybody that have not responded to the event. Removing it from their calendar and preventing them to say "yes" to the event.