WebSocket text frame impl is broken

[987Nabil]

We convert from netty by calling text on TextWebSocketFrame. This is only valid, if it is the final frame.
Else we might have half a UTF8 char in a TextWebSocketFrame. TextWebSocketFrame should be transformed to a data structure that keeps the bytes for later aggregation if it is not final.
This might turn out tricky. I am not sure, this is fixable in binary compatible way.

[mberndt123]

If the aggregation behaviour is implemented, there should be a configuration parameter to limit the maximum size to avoid DoS.