Allow data-url to customize which params are sent as headers ~21

[justinbmeyer]

trafficstars

todoConnection(["uses-session"],{
    url: {
        getListData: "GET /todos",
        headers: ["sessionId"]
    }
})

todoConnection.getListData({sessionId: 7, complete: true})

// GET /todos?complete=true
// Headers:
//  sessionId=7

[justinbmeyer]

alternatively, there needs to be an implied reading of session info for all requests.