OPT: check_dependences: display number of cores (issue #621)
OPT: check_dependences: display number of cores (issue #621)

Former-commit-id: fb4666f0cd2ea8c858a15a93876ba064b0cbbfae [formerly f989016601e3e155d0620f166de20a095a418182]
Former-commit-id: 88132109ffdf782814180c9969b104559b0af4c3
Former-commit-id: 2152d1e190fe2d0f09142e83b87452d4504807d0
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox