reconnection could be handled when the need is directly noticed on transport level

[pratman]

Right now methods:

• on_ws_fail
• on_ws_close

of wamp_websocketpp_websocket_transport are private.

These are the methods that are called when:

1. Connection fails (on_ws_fail)
2. Connection closes (on_ws_close)

There are no possibilities for the user to directly react on these cases and try to reconnect only when needed. This forces to use frequent connection checkers.