Split packaging into m2ee-tools and python-m2ee

Also, drop dependency on python-simplejson, as the json module that is
included in python 2.6 will be used instead already.
debian: release 0.5.3-2

DOES NOT properly backport to squeeze without changes, dunno what
those changes are right now, dh_python2 is a bit weird. It builds ok on
wheezy, but with dh_python2 in squeeze you get an empty package.