OAuth 1.0: allow requesting temporary token with `GET` method
Currently, both the signond and gsignond plugins make a
POST request when getting the temporary token, as recommended by the spec. However, the spec allows other methods to be used, and it appears that SmugSmug only responds to
So we need to add a parameter to allow to use
GET too. I propose calling it
RequestMethod, and if unspecified it should continue using
I'll implement the change in the signon-oauth-plugin project.