activate jvm option to prevent [missing trace] exceptions

[GoogleCodeExporter]

there's a JVM option for that, see 
https://groups.google.com/d/msg/clojure/Y2OMW26GoFc/F7p1ZZ2i1iYJ

the idea would be to systematically:

- add this option when ccw launches a repl by itself (not through a leiningen 
jvm)
- pass this option to leiningen when starting a leiningen jvm *for a REPL* (not 
for launching a leiningen jvm through the generic command line => there we want 
to interfere as little as possible with the user xp one would have if started 
through a shell)

Original issue reported on code.google.com by laurent....@gmail.com on 4 Dec 2014 at 11:26