Adding mime.define support.

[amirbilu]

I was wondering whether it would be possible to support mime.define - https://github.com/broofa/node-mime#mimedefine -.

I can have it written and pull request.
Will you find it useful?

Many thanks.

[MathieuLoutre]

Interesting. I think it would be useful if you think it's useful. However, we did change the MIME lib a while ago to generate the full content type header because of encoding problems (which is much nicer) and we're using this library to do it: https://github.com/jshttp/mime-types
However it seems it doesn't have the ability to define custom types. If you're willing to tinker a bit or see a solution/other lib, I'm willing to take a PR (as long as we conserve the full content type header).