new adjustments for some functions

@pravsripad , I still think the editing in function ' plot_compare_brain_responses' is redundant. If I misunderstant you suggestion, please let me know. I also recorrect some bugs in functions 'apply_ica',  'apply_create_noise_covariance'.
If path is None, then we get an error trying to make file '/plot_compare_109925_CAU01A_100715_0842_2_c,rfDC,bp1-45Hz,ctpsbr.png'...