Update todomvc-common of vanillajs example

Hi!

I think I've found a minor error on this page: http://todomvc.com/examples/vanillajs/ .

`vanillajs` example page doesn't show the side column at the moment, and the reason seems that the path detection of `/learn.json` is not correct, and that is caused by the old version of base.js.

Then I updated todomvc-common dependency of vanillajs example (using `bower install` command).

Thanks,