Simplify usage by supporting new default loop and new Socket API

[clue]

This changeset simplifies usage by supporting the new default loop.

// old (still supported)
$connector = new \Ratchet\Client\Connector($loop);

// new (using default loop)
$connector = new \Ratchet\Client\Connector();

ReactPHP now implements the logic that previously lived inside the connect() function itself. This means that although this removes a bunch of code, this should not affect BC at all.

Builds on top of reactphp/event-loop#226, reactphp/event-loop#229, reactphp/event-loop#232, reactphp/socket#260, reactphp/socket#264 and #124