[json] fix json serialization for recent simplejson implementation, and test encoding of entities
as with earlier simplejson implementation, iterencode internal stuff
is a generated function, we can't anymore rely on the _iterencode
overriding trick, so move on by stoping isinstance(Entity, dict).
This is a much heavier change than expected but it was expected
to be done at some point, so let's go that way.
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/web usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/shared/data usr/share/cubicweb/cubes/shared
debian/tmp/usr/share/cubicweb/cubes/shared/wdoc usr/share/cubicweb/cubes/shared