Adding some config functionality

bip/data/config/config.toml

bip/main.py

bip/pipelines/dMRI_diff/diff_gdc.py

bip/pipelines/dMRI_fieldmap/fieldmap_post_topup.py

bip/pipelines/fMRI_rest/rfMRI_prepare.py

bip/pipelines/fMRI_task/tfMRI_prepare.py

bip/pipelines/struct_T1/T1_gdc.py

bip/pipelines/struct_T2_FLAIR/T2_FLAIR_gdc.py

bip/pipelines/struct_asl/asl_proc.py

bip/pipelines/struct_swMRI/swMRI_gdc.py

bip/pipelines/struct_swMRI/swMRI_proc.py

bip/utils/__init__.py

bip/utils/get_b0s.py

bip/utils/get_dwell_time.py

bip/utils/log_utils.py

bip/utils/read_json_field.py