update app to use yahoo weather api

[kaycebasques]

@marcacohen @petele please review my updates to use the Yahoo Weather API.

So far I've only made the updates in the final directory. Once we're all on the same page I'll update the other directories.

[kaycebasques]

Adding comments to the commits now...

[petele]

To fix the app.hasRequestPending issues:

1. In initialWeatherForecast add created: '2016-07-22T01:00:00Z', to the object (line ~12)
2. Remove hasRequestPending from the app object, (line ~46)
3. Add var dataLastUpdated = new Date(data.created); to the top of app.updateForecastCard
4. Add the following below var card = app.visibleCards[data.key]

    // Verifies the data provide is newer than what's already visible
    // on the card, if it's not bail, if it is, continue and update the
    // time saved in the card
    var cardLastUpdatedElem = card.querySelector('.card-last-updated');
    var cardLastUpdated = cardLastUpdatedElem.textContent;
    if (cardLastUpdated) {
      cardLastUpdated = new Date(cardLastUpdated);
      // Bail if the card has more recent data then the data
      if (dataLastUpdated.getTime() < cardLastUpdated.getTime()) {
        return;
      }
    }
    cardLastUpdatedElem.textContent = data.created;

1. Add results.create = json.query.created; to the caches.match and XHR in app.getForecast
2. In index.html, add <div class="card-last-updated" hidden></div> to the card template.

I'll send you the JS file with my updates.

[petele]

LGTM! Thanks @kaycebasques!!

[kaycebasques]

cool thanks @petele I'll clean up the code and then merge

[kaycebasques]

I also need to update the rest of the directories...