test_matrices: Changed exception type used to communicate
test_matrices: Changed exception type used to communicate

In test_LUdecomposition_Simple_iszerofunc() and
test_LUdecomposition_iszerofunc(), changed the exception type
used to communicate from inside LUdecomposition() and
LUdecomsposition_Simple() to Exception. The previous exception type,
StandardException, is not in Python 3.3.
Communicates with args[0] member of Exception instance.

kaushik94/sympy,kaushik94/sympy,kaushik94/sympy