title: DataTable global filtering not working as expected when using columns templates
body: <p>i'm trying using global filtering width PrimeNG dataTable template columns, but filter behave weird and not working as expected</p>
  
  <pre class="lang-html prettyprint-override"><code>Global filter: &lt;input #gb pInputText type="text"&gt;
  &lt;hr&gt;
  &lt;p-dataTable [value]="cars" [globalFilter]="gb"&gt;
      &lt;p-column field="vin" header="Vin"&gt;
        &lt;template let-col let-car="rowData" pTemplate="body"&gt;
             {{car[col.field]}}
          &lt;/template&gt;
      &lt;/p-column&gt;
      &lt;p-column field="year" header="Year"&gt;
        &lt;template let-col let-car="rowData" pTemplate="body"&gt;
            {{car[col.field]}}
          &lt;/template&gt;
      &lt;/p-column&gt;
      &lt;p-column field="brand" header="Brand"&gt;
        &lt;template let-col let-car="rowData" pTemplate="body"&gt;
            {{car[col.field]}}
          &lt;/template&gt;
      &lt;/p-column&gt;
      &lt;p-column field="color" header="Color"&gt;
          &lt;template let-col let-car="rowData" pTemplate="body"&gt;
            {{car[col.field]}}
          &lt;/template&gt;
      &lt;/p-column&gt;
  &lt;/p-dataTable&gt;
  </code></pre>
  
  <p>I made <a href="http://plnkr.co/edit/DW7Tun?p=preview" rel="nofollow noreferrer">plunker</a> to demonstrate the issue</p>
  
  <p>Thanks!</p>