Correct supported Python versions in setup.cfg
Correct supported Python versions in setup.cfg

Remove claims of Python 3 support until we get around to implementing
Python 3 support.

Change-Id: I8b1aba541879ce6dbd7af7d7da47dd3a2bf32366

austin987/bandit,pombredanne/bandit,stackforge/bandit,stackforge/bandit,pombredanne/bandit,chair6/bandit