add client close frame

An old realization of ws client was cause of exception in server part in time of disconnecting.
Add right code for correct disconnecting.
According to its breakdown of a frame (at http://tools.ietf.org/html/rfc6455#section-5.2), you're setting the payload length as zero (the last seven bits of 0x8880). But you're including a close reason in the payload data, so your payload length isn't zero. So, this close frame seems malformed for that reason alone.

But the body itself is malformed according to [5.5.1](http://tools.ietf.org/html/rfc6455#section-5.5.1)

> If there is a body, the first two bytes of the body MUST be a 2-byte unsigned integer (in network byte order) representing a status code with value /code/ defined in Section 7.4.

And

> Close frames sent from client to server must be masked

(You're not even dealing with a masking key, right?).

The solution is to instantiate a new `Wrench\Frame\HybiFrame`, use `encode($payload, Protocol::TYPE_CLOSE, $masked = true)` to build the close frame properly, and then send `$frame->getFrameBuffer()` down the socket. That'll take care of constructing the frame, dealing with the length, and masking it properly.

You should also be careful to meet 5.5's requirement that:

> MUST have a payload length of 125 bytes or less

(And we use a `Frame` not a `Payload` because control frames must not be fragmented.)