Used absolute urls for each exercise and challenge, for easier sharing.
Used absolute urls for each exercise and challenge, for easier sharing.

chenleo/ipynotebook,nntisapeh/intro_programming,ehmatthes/intro_programming,nntisapeh/intro_programming,chenleo/ipynotebook,chenleo/ipynotebook,BadWizard/intro_programming,BadWizard/intro_programming,BadWizard/intro_programming,chenleo/ipynotebook,nntisapeh/intro_programming,ehmatthes/intro_programming,nntisapeh/intro_programming,BadWizard/intro_programming,ehmatthes/intro_programming,ehmatthes/intro_programming