Move performance playground

The playground originated as doing qthreads performance testing alongside of
fifo and devolved into a testing a bunch of different performance related
things. I believe having the playground around is useful longterm to
investigate performance related things without having to manually kick off
runs. However, it's not useful being on the main performance webpage and is
confusing to most people on the core team and almost certainly all people off
the core team.

This just moves it from being part of the main performance page to being on
it's own that is not publicly linked.

As in, instead of being at chapel.sourceforge.net/perf/chap04, it will be
at chapel.sourceforge.net/perf/chap04/playground and
chapel.sourceforge.net/perf/chap04 no longer has the multi-configuration
options