Add support for h-events

[jamietanna]

It'd be quite useful to have a front-end for publishing events to my site via Micropub (via form POST).

Would this be something you'd be interested in if I contributed it via a PR?

[barryf]

Sounds great. I'd be happy to accept a PR. Let me know if you need any help.

I originally intended adding h-event -- and built my site's software to handle it -- but realised I didn't often need to create events.