When a user clicks on "BrowserID Login", one of three things will happen
1- If they have an account, they will login
2- If they don't but there is one authinstance with browserid is present
    AND it has weautocreateusers enabled, then they will get an account
    in that institution, and login
3- If none of the above is true, they will get redirected to a register
    page, which follows same self registration pattern as the internal
    authentication with the "confirm email" step removed.

Change-Id: Idde3166e0664bf2acdc1da32271125e91d43af9c
Signed-off-by: Hugh Davenport <hugh@catalyst.net.nz>