BUG: sct_propseg now check if input images are nifti format. Fixed #362
BUG: sct_propseg now check if input images are nifti format. Fixed #362

Former-commit-id: c43bc0d26720e6e0d7e8f75990d84a99fb9b9097 [formerly 442adb2e1e33c57c3d0adb48321e725f6d4e5f09]
Former-commit-id: 45f2ea3c76b6ac3417f097f7f5bb04138209405c
Former-commit-id: 8c3614d1b09835a2edb299ee1bfdbef5c83f352c
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox