Add support for <input type="week"/>

[benlesh]

This is to add support for the week input type. This follows the HTML5 spec which specifies using ISO-8601 standards for identifying dates. As such, the date output to the model is the Thursday of the week. Per ISO-8601, the "first week" of the year is whatever week has the first Thursday of the year.

Also added output for week-of-the-year to $filter('date'). This allows the date of the year to be output as follows:

 var value = new Date(2013, 0, 12); // Jan 12, 2013
 console.log($filter('date')(value, 'yyyy-Www'); // 2013-W01

[benlesh]

Again, I'm not sure how you'd like me to separate these PRs, but I'm sure I can do some Git gymnastics to separate them if necessary.

[benlesh]

This is associated with PR #5256 and #5422

[benlesh]

Also, as I noted in the other PR, I noticed the scenarios for the documentation are failing. It's late though, so I'll fix those sometime soon.

[benlesh]

closed in favor of #5864