Add support for temporary credentials + pull request #44

[sebasmonia]

This PR adds token to the Dyna struct as an optional parameter. When the token is present, a header for it is included in the request.

I also included PR #44 because I needed it to prevent errors when loading. Thanks to @rayslava.

[rayslava]

@rudolph-miller could you merge this one so at least build works and the package can be returned to quicklisp?