Change OAuth process to allow bipedal for newer client versions which support it

[dobey]

To make the user experience better, and limit the amount of user interaction, we want to use bipedal OAuth to register a computer to the user's account. Doing so will greatly simplify the code on the client side. We'll need to only do this for clients of a particular version or newer, as we'll need to support the tripedal method for older clients, and third party clients using the tomboy REST API for notes, but this should be a relatively simple change.