COMETD-507 - Allow maxNetworkDelay to be modified dynamically.

Now BayeuxClient forwards options to transports, and transports
lookup the maxNetworkDelay dynamically so that it could have a
different value for every message.
Updated to Jetty 9.1.3-SNAPSHOT.
Merged branch '2.8.x' into 'master'.
Fixed compilation issue.
COMETD-505 - Synchronous CORS requests do not work in jQuery + Firefox.

Worked around jQuery bug.
Merged branch '2.8.x' into 'master'.
COMETD-506 - Failed subscriptions should remove listeners.

Implemented proper removal of listener in case of subscription
failures. This was only needed in the Java client, since the
JavaScript client already had this feature as part of COMETD-459.
Merged branch '2.8.x' into 'master'.
Fixed locking between ServerSessionImpl and AckExtension.
Updated Jetty to 9.1.3.v20140225.
Better handling of configuration parameters.
Improved notification of MaxQueueListeners.
COMETD-510 - Handshakes failed to be sent are leaked.

Fixed by invoking the right method upon exception thrown
by HttpClient.send().
COMETD-511 - Ack extension may lose messages.

Rewrote the acknowledgement extension (server-side) to behave
correctly in case of non-normal arrival of /meta/connect requests.

Introduced a new listener, ServerSession.QueueListener, that is
notified when a message is added to the session queue.

The new implementation of the acknowledgement extension now
relies on ServerSession.QueueListener and on the existing
ServerSession.DeQueueListener to store messages at the correct time
and to replace the queue at the correct time.
COMETD-512 WebSocketTransport should close the connection when expiring.

When a message expires due to maxNetworkDelay, the connection
is now closed with message 'Expired'.
COMETD-513 - Client-side half-closed connections should discard server messages.

The implementation now uses a different WebSocket endpoint per
connection, so that an old endpoint can detect whether it should
discard messages (because they belong to a closed connection).
Merged branch '2.8.x' into 'master'.
Removed messageId parameter from ServerSession.deliver(),
in line with what already done for ServerChannel.publish().
Modified signature of service methods invoked by AbstractService
to be in line with what done when using annotations.
COMETD-511 - Ack extension may lose messages.

Fixed race in the new implementation, where a thread could read
the wrong batch number and send it in the /meta/connect response.