[#2939] Fix SslContext usage in the examples for client side

Motivation:

We incorrectly used SslContext.newServerContext() in some places where a we needed a client context.

Modifications:

Use SslContext.newClientContext() when using ssl on the client side.

Result:

Working ssl client examples.
HTTP/2 Codec Read/Write Restructure

Motivation:
The HTTP/2 codec has some duplication and the read/write interfaces are not cleanly exposed to users of the codec.

Modifications:
-Restructure the AbstractHttp2ConnectionHandler class to be able to extend write behavior before the outbound flow control gets the data
-Add Http2InboundConnectionHandler and Http2OutboundConnectionHandler interfaces and restructure external codec interface around these concepts

Result:
HTTP/2 codec provides a cleaner external interface which is easy to extend for read/write events.
Send a websocket close frame with status code when receiving invalid frames

Motivation:

According to the websocket specification peers may send a close frame when
they detect a protocol violation (with status code 1002). The current
implementation simply closes the connection. This update should add this
functionality. The functionality is optional - but it might help other
implementations with debugging when they receive such a frame.

Modification:

When a protocol violation in the decoder is detected and a close was not
already initiated by the remote peer a close frame is
sent.

Result:

Remotes which will send an invalid frame will now get a close frame that
indicates the protocol violation instead of only seeing a closed
connection.