title: add properties of object in array and get single object by loadash
body: <p>I am using loadash in my project 
  i have object in array like this </p>
  
  <pre><code>[{
      "rating": {
          "time_to_table": 5,
          "value_for_money": 5,
          "innovation": 5,
          "plating_decoration": 5,
          "taste": 5
      }
  }, {
      "rating": {
          "time_to_table": 0,
          "value_for_money": 3,
          "innovation": 2,
          "plating_decoration": 2,
          "taste": 4
      }
  }]
  </code></pre>
  
  <p>Now I want output like this by adding each property and want single object like this </p>
  
  <pre><code>"rating": {
      "time_to_table": 5,
      "value_for_money": 8,
      "innovation": 7,
      "plating_decoration": 7,
      "taste": 9
  }
  </code></pre>
  
  <p>I have tried this </p>
  
  <pre><code>        var obj = {
              "time_to_table": 0,
              "value_for_money": 0,
              "innovation": 0,
              "plating_decoration": 0,
              "taste": 0,
              "total" : 5 * data.length
          }
  
          _.forEach(data,function(d){          
              obj.time_to_table += d.rating.time_to_table;
              obj.value_for_money += d.rating.value_for_money;
              obj.innovation += d.rating.innovation;
              obj.plating_decoration += d.rating.plating_decoration;
              obj.taste += d.rating.taste;
          });
  </code></pre>