This fixes up the calling and propagates the contexts for the backends which use lib/rest.
git grep -l github.com/ncw/rclone | xargs -d'\n' perl -i~ -lpe 's|github.com/ncw/rclone|github.com/rclone/rclone|g' goimports -w `find . -name \*.go`
This was started by Fionera, finished off by Laura with fixes and more docs from Nick. Co-authored-by: Fionera <fionera@fionera.de> Co-authored-by: Nick Craig-Wood <nick@craig-wood.com>