Mark Tests/SubsMat/acc_rep_mat.pik as binary to solve Pickle problem

If the pickle file has DOS/Windows newlines which can happen under
Windows depending on how git was configured, the C based pickle code
in Python 3.4 fails to to load it with this exception:

_pickle.UnpicklingError: the STRING opcode argument must be quoted

See test_SubsMat.py and this thread on the mailing list for background:
http://lists.open-bio.org/pipermail/biopython-dev/2014-April/011274.html