Update Jetty from 7.4 to 9.1

It will be great to keep it as close to upstream as possible. Since 9.1.x is already added, 9.2.1 is doable with less effort?

Here are some compelling reasons for upgrading to 9.2.x
https://webtide.com/jetty-9-2-0-released/

9.2.1 is the latest release available as of today.

It is possible to update Jetty before 3.10.0 final release?
http://download.eclipse.org/jetty/stable-9/dist/

There have been some additional API changes in the 9.2.x release line as compared with our current version (Jetty 9.1.5.v20140505). Not sure that this will make it for 3.10.0 ... but perhaps for a 3.10.1 release.

3.10 Beta is showing "0:0:0:0:0:0:0:0" near the 5222 port in Admin Console. It was showing "All addresses" in 3.9.3. Some kind of IPv6 support added in Jetty 9.1? Maybe it's a minor thing, but still would be nice to fix.

@wroot That might be related to the Mina upgrade (Mina manages the C2S ports). Probably worth a separate ticket to see if we can clean that up.