Change version number to 1.0.15

ltfatpy/tests/gabor/test_phaselock.py

ltfatpy/tests/gabor/test_phaseplot.py

ltfatpy/tests/gabor/test_phaseunlock.py

ltfatpy/tests/gabor/test_plotdgt.py

ltfatpy/tests/gabor/test_plotdgtreal.py

ltfatpy/tests/gabor/test_s0norm.py

ltfatpy/tests/gabor/test_sgram.py

ltfatpy/tests/gabor/test_tfplot.py

ltfatpy/tests/signals/test_greasy.py

ltfatpy/tests/signals/test_gspi.py

ltfatpy/tests/signals/test_linus.py

ltfatpy/tests/sigproc/test_fir2long.py

ltfatpy/tests/sigproc/test_firkaiser.py

ltfatpy/tests/sigproc/test_firwin.py

ltfatpy/tests/sigproc/test_groupthresh.py

ltfatpy/tests/sigproc/test_largestn.py

ltfatpy/tests/sigproc/test_largestr.py

ltfatpy/tests/sigproc/test_long2fir.py

ltfatpy/tests/sigproc/test_normalize.py

ltfatpy/tests/sigproc/test_rms.py