Websocket resources should have their keepalive timers reset whenever a
message comes in. This is a nicety that slightly reduces the amount of
traffic we send when actively messaging.
Previously this was handled by MessageReceiver, but it's a bit cleaner
to just have the WebsocketResource add an extra 'message' event handler.
// FREEBIE
By default, automatically disconnect if no response. This is preferable
because we can sometimes lose connectivity without receiving a close
event from the socket, but it's also possible that the endpoint may not
support responses.
// FREEBIE
We now disconnect ourselves if we don't get the server's response to a
keepalive request within 30s. This way we will eventually disconnect if
the network goes away but the socket is not closed.*
* See code.google.com/p/chromium/issues/detail?id=197841 and
https://stackoverflow.com/questions/11755605/chrome-websocket-connection-not-closed-when-browser-closed
We will then try to reconnect once a minute (See 8a10c96);
Keepalives belong at this level anyway, since the format is defined by
both the websocket resource protocol and our specific server url
structure.
// FREEBIE
