Support for blob/non-json requests

[chriskuech]

From what I can tell, this module allows you to access the raw body of the request as a Buffer, but there is no way to disable still parsing it as JSON. I would like to use this to access the raw binary of the request, which would require--

• not parsing the body as JSON
• associating * content type (excluding application/json) with the raw body parser

[chriskuech]

I actually got this working without the library:

  app.addContentTypeParser('*', { parseAs: 'buffer' }, (req, body, done) => {
    return Buffer.isBuffer(body)
      ? done(null, body)
      : done(new Error('Invalid body'))
  })

[Eomm]

Reopening as it seems a good use case