Deal with the "Allow SE.com/SO.com/M.SE.com to use this openid" page

[Manishearth]

Since the SE openid is integrated, on some sites there is no confirmation message unless you enter it as a custom openid. We're doing the latter here, so we should probably automatically do the confirmation, OR switch to the built in mechanism (which is a bit roundabout)

Related: #8 as well