python - ex: Add code and prime unittests.

Log Message:
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Add code and prime unittests.
code.py tests the Mapping class and the relativity of States and Classes.
prime.py tests the CodeClass Mapping to insure that the expected exception
is actually retrieved from ErrorLookup.

Added Files:
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ex/test:
code.py (r1.1)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/ex/test/code.py?rev=1.1&content-type=text/x-cvsweb-markup)
prime.py (r1.1)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/ex/test/prime.py?rev=1.1&content-type=text/x-cvsweb-markup)