Simplify usage by supporting new default loop

[clue]

This changeset simplifies usage by supporting the new default loop.

// old (still supported)
$factory = new Clue\React\Quassel\Factory($loop);

// new (using default loop)
$factory = new Clue\React\Quassel\Factory();

Builds on top of reactphp/event-loop#226, reactphp/event-loop#229, reactphp/event-loop#232 and reactphp/socket#260
Also builds on top of #53 and #55 to skip tests that exhibit a rare race condition