Enable automatic connection recovery by default

[michaelklishin]

Automatic connection recovery has been around for about 2 years in this client and some 5 years total (starting with the amqp gem in Ruby, then Bunny, then Java client, March Hare and Langohr). With a round of fixes up to and in Java client 3.6.6 we know that it works quite well in practice and what kind of bugs and tricky aspects we've discovered over the years. It's time to enable it by default.