PyTest with coverage tests and proper gitignore

Not much but this improves the testing experience by

 - Not tracking temporary stuff that was created during tests
 - Creating a coverage statistic to see how much of the code is actually tested:

        ==================================================== test session starts ====================================================
        platform darwin -- Python 2.7.8 -- py-1.4.26 -- pytest-2.6.4
        plugins: cache, cov, pep8
        collected 147 items 

        tests/test_argspec.py ....
        tests/test_pysoundfile.py .....................................................................s.........................................................................
        -------------------------------------- coverage: platform darwin, python 2.7.8-final-0 --------------------------------------
        Name                     Stmts   Miss  Cover   Missing
        ------------------------------------------------------
        pysoundfile                360     31    91%   379, 463, 484-486, 502-505, 762-765, 772, 782, 887, 1037-1041, 1085, 1094, 1099, 1102, 1104, 1126, 1198, 1209, 1225-1228
        setup                       12     12     0%   2-16
        tests/test_argspec          48      0   100%   
        tests/test_pysoundfile     436      4    99%   404-407
        ------------------------------------------------------
        TOTAL                      856     47    95%