turn wikistats into module

delete the misc/wikistats.pp, split the classes
and definition into files in a module..

this is just used in labs on wikistats.wmflabs.org

not to be confused with stats.wm.org by ezachte/analytics

next step i will try and replace the Apache setup classes
with the newer system, since this is a good test service

Change-Id: I99dc8657b2c1fe1d7f28e5941fd7c5dc05f1c6c6