Switch default to nonblock #515

We saw Docker connection hanging and Timeout.timeout not helping, would be great if nonblock was the default so that other developers wouldn't run into the same issue.

http://www.mikeperham.com/2009/03/15/socket-timeouts-in-ruby/
https://spin.atomicobject.com/2013/09/30/socket-connection-timeout-ruby/
https://github.com/excon/excon/search\?utf8\=%E2%9C%93\&q\=nonblock\&type\=

I can open the PR if you want.