title: disable cell when user click on 'add new' in ng2-smart-table
body: <p>My settings are as given below. 
  when I click on the 'add new' link the ID cell is editable. We want to make that field uneditable.</p>
  
  <pre><code>mySettings = {
  columns: {
          id: {
              title: 'ID',
              editable: false,
          },
          name: {
              title: 'Name',
          },
          lastname: {
              title: 'Last Name',
          },
      }
  };
  </code></pre>