Add scripts for distillability modelling

extract_features.js

-return (function() {
-  function hasOGArticle() {
-    var elems = document.head.querySelectorAll(
-        'meta[property="og:type"],meta[name="og:type"]');
-    for (var i in elems) {
-      if (elems[i].content && elems[i].content.toUpperCase() == 'ARTICLE') {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  var body = document.body;
-  return {
-     'opengraph': hasOGArticle(),
-     'url': document.location.href,
-     'numElements': body.querySelectorAll('*').length,
-     'numAnchors': body.querySelectorAll('a').length,
-     'numForms': body.querySelectorAll('form').length,
-     'innerText': body.innerText,
-     'textContent': body.textContent,
-     'innerHTML': body.innerHTML,
-  }
-})()