Add angular-social widgets to product page

@tsanko 

### Add angular-social to Vanilla product page

Project found at: https://github.com/esvit/angular-social

###### Issues:
- Getting an error ```Cannot read property 'total_count' of undefined``` because when the Facebook directive goes to fetch the current share count it returns ```undefined``` instead of ```0```.
- The CSS and JS was added to ```index.html``` manually and not dynamically injected with ```grunt build```

###### Note about implementation:
- Below is how the project is added to the HTML by default
  - If you remove ```data-url``` the directive will default to ```$location.absUrl()``` and fetch the current URL.
  - The properties ```data-description``` and ```data-image``` are only being used by the ```ngSocialVK``` directive - a European/Russian social network, thus those properties have been removed from our version.
```html
<ul ng-social-buttons
     data-url="'http://news.mistinfo.com/'"
     data-title="'test'"
     data-description="'test2'"
     data-image="'http://s3.mistinfo.com/32/d8/32d8eab76f4c242f665bda66b5edc6c5.jpg'">
    <li>Share:</li>
    <li class="ng-social-facebook">Facebook</li>
    <li class="ng-social-google-plus">Google+</li>
    <li class="ng-social-twitter">Twitter</li>
    ...
</ul>
```
- Here is how the HTML looks in Vanilla

```html
<ul ng-social-buttons
     data-title="product.name"
     class="th-icon-group">
    <li class="ng-social-facebook">Facebook</li>
    <li class="ng-social-twitter">Twitter</li>
    <li class="ng-social-pinterest">Pinterest</li>
</ul>
```

Overall it seems to be working well. Just needs to be tested with some metadata.