check for Python 3.2

in setup.py and init

treats unsupported 3.x < 3.3 like unsupported 2.x
don't ensure_ascii in JSON messages in Session
Merge pull request #5500 from minrk/check-3.3

check for Python 3.2
Merge pull request #5628 from minrk/no-ensure-ascii

don't ensure_ascii in JSON messages in Session
Do not record memory addresses of display objects in repr
Add test for DisplayObject.__repr__