use clojure 1.6 final, add 1.7 snapshot profile
clojure.pprint require derp
change socket closing behaviour to accommodate JDK 1.8 changes, fixes NREPL-56
Add Java version info to op "describe"'s response, NREPL-57
Update session before sending eval response messages.
eliminate source of thread leak, NREPL-40:
The flailing `future` call is obvious in hindsight. Note that
thread counts (observed via jconsole or other tools) decay after some
delay (a detail of the `.cancel` of Clojure's Future implementation,
I'm guessing).

Thanks to David Lao for the report.
0.2.4 changelog
[maven-release-plugin] prepare release tools.nrepl-0.2.4
[maven-release-plugin] prepare for next development iteration