Replaced slideshare by OSF for hosting the London course (#2134)
Replaced slideshare by OSF for hosting the London course (#2134)

... because i HATE slideshare

Former-commit-id: d5b0aca03918660db621f75eac314aca79048f51
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox