REF: removed extension in sct_convert to avoid problem when script is not in PATH
REF: removed extension in sct_convert to avoid problem when script is not in PATH

Former-commit-id: 5c8604421bdd775e224f50f4dede8ca5d60d6697 [formerly 0603fb29687d4d775592bb8650853b32a159d01b]
Former-commit-id: b6da5f6ab45964288898449a82d1eb1d48a8ccf5
Former-commit-id: 31aa180ec13f10236014b2a9720eff094a328ecd
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox