ts+backbone: Fixed syntax, extracted constant
ts+backbone: Replaced CDN dependencies with locals
ts+backbone: Fixed footer, remaining count

The remaining todos counter was the same bug fixed in
89e5d5c7afc8e2f1a27bdbd436dfd83dc36fc3b3.

\#main and \#footer weren't hidden if there were no todos in the list.
Merge pull request #450 from passy/ts-backbone-update

Ts backbone update