Remove type query parameter from OAuth2 requests.

While the type parameter was required in older versions of the OAuth2
specification, it was removed in version 8. Currently, this breaks OAuth2
against the Dropbox API. Closes #127.

http://tools.ietf.org/html/draft-ietf-oauth-v2-08#section-4.1.1
Merge pull request #154 from bradgignac/remove-type-parameter

Remove type query parameter from OAuth2 requests.