Pull fixes for #1073 (Lantern hanging on missing fallback proxy)

@myleshorton - @skivvies and I agreed that the best way to reduce the confusion and perception of brokenness here is to launch the Google sign-in in a new browser window.  This branch does that, and also fixes some issues that we had with the display of the "Can't reach any users ..." message in the footer.

Note - I had to modify LanternBrowser, which I built targeting OS X 10.6 64 bit.

@myleshorton If you're comfortable with this UI change, please go ahead and merge the pull request.  Otherwise, let's talk :)