NEW: sct_utils: added module "add_suffix"
NEW: sct_utils: added module "add_suffix"

Former-commit-id: c9ac9ee380a449259fb7492c8fe25905c301538d
Former-commit-id: e0515d57228dcd8d4b8fe11d910669f65b5ac23b
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox