v1.8.0

A major new feature release, see release announcement.

• Feature: Simplify usage by supporting new default loop.
  (#182 by @clue)

  // old (still supported)
  $factory = new React\Dns\Resolver\Factory();
  $resolver = $factory->create($config, $loop);
  
  // new (using default loop)
  $factory = new React\Dns\Resolver\Factory();
  $resolver = $factory->create($config);