Decide how to handle multiple meek backends in Tor Launcher
I made a 3.6.3-meek-2 release that has a meek capable of using both [[doc/meek#GoogleAppEngine|Google App Engine]] and [[doc/meek#AmazonCloudFront|Amazon CloudFront]] as backends.
The idea behind having two (or more) is that one may work where another does not. The question is, how to usefully present the option? How is the user supposed to choose between them?