Add "Access-Control-Allow-Methods" to the OPTIONS HTTP method

[yoshuawuyts]

Feature Request

#104 introduces the OPTIONS HTTP method for CORS support. In order to get it to work, the Access-Control-Allow-Methods header has been omitted for now.

Detailed Description

We should reintroduce Access-Control-Allow-Methods through its own CORS middleware.

Context

This is a nice addition to our CORS capabilities.

Possible Implementation

See #104 (comment) for a discussion on what was difficult in adding this. As per #104 (comment) it's been suggested this should probably be its own middleware