Merge pull request #70 from rakyll/master

Remove unused multipart-parser dependency
Adding basic and multipart media upload.
Don't append params if there are none.
application/json responses are automatically handled and decoded, don't need to rely on request anymore.
Removing explicitly set charset.
Adding tests.
Adding media upload docs to the README.
Merge pull request #21 from rakyll/media

support for media upload
Releasing 0.4.0.