Updated src/batcher/base.py to adapt to mat files and RVHR data

[ShiyuBelleWang]

1. Updated the src/batcher/base.py file so that a) the script will read .mat files for the resting-fMRI BOLD signal (Schaefer ROIs were used as an example as specified in train.py - default_args.data); b) in addition, it will load physiological files (RV and HR) and save them along with the fMRI time courses
2. Updated the tool/data file to read in mat files

[rgbayrak]

@ShiyuBelleWang The PR suggest the only changes are made to src/batcher/base.py however I see data.py file is also changed. Please change your PR explanation to include all the changes you made to all files. Once it is done, I will merge the PR.