Add `requests` as a resource type

[dossy]

Problem

Currently, in the Dashboard, you can view an event and if its source isn't Automatic, such as API, it links to a page with a URL like /logs/req_<id>.

The data provided on that page would be very useful as an API response, especially when needing to find out the source/originator of an API request.

Feature

Being able to use the CLI to do something like this:

$ stripe get req_<id>

$ stripe requests retrieve req_<id>

[dossy]

FWIW, I tried to see if this kind of dirty hackery would do anything useful:

$ stripe get --live ../logs/req_<id>

Unfortunately, it gets this error response (no surprise, tbh):

{
  "error": {
    "message": "Unrecognized request URL (GET: /logs/req_<id>). Please see https://stripe.com/docs or we can help at https://support.stripe.com/.",
    "type": "invalid_request_error"
  }
}

Wishful thinking, figured I'd at least give it a try. :-)