Template.create, Template.update, Template.delete

[begedin]

This PR adds support for Template.create, .update and .delete

To enable this support, while following existing conventions as much as I could, I also had to define %Template{} and %Template.Response{} structs.

This PR still doesn't add support for Template.get/retrieve or Template.list

Since Template.delete seems to be the first supported endpoint which returns a 200 with a blank map as the response body, I extended support for automated body results decoding by checking if the decoded body has a results key.

I'm aware that there's the decode_results option I could've used, but that seems only specific and not very clean. If it's preferable for me to use that, I can update the PR.

[ewandennis]

Hey @begedin - thanks for the PR! Will review asap.

[joshsmith]

@ewandennis any progress on this at all?