Add callback for modifying Server before starting

[hlship]

I'm attempting (and its a bit of a leap!) to integrate New Relic monitoring into our app; I'm having to do some ugly alter-var-root stuff to hack things so that I can intercept the incoming servlet request and response.

It would be nice if an option to qbits.jet.server/run-jetty was a callback function that could tweak the Server instance before it is started.

[mpenet]

I was actually thinking about adding that. I ll see what I can do later today

[mpenet]

well you can do it already, see the configurator option.

https://github.com/mpenet/jet/blob/master/src/clj/qbits/jet/server.clj#L193-L194

This is documented nowhere tho and it's probably a left-over from the jetty-adapter copy pasta