title: PrimeNG table dropdown edit not working with label
body: <p>I am using latest version PrimeNG table for listing records in Angular 4. But I am facing issue with editing the record through <code>p-drowpdown</code>. If I am selecting any of the data from the dropdown then its value field is displaying in column, which should be label field instead. </p>
  
  <pre><code>&lt;p-column field="id" header="Name"  [sortable]="false" resizableColumns="true"
  [filter]="true" filterPlaceholder="Search" [editable]="true" [style]="{'overflow':'visible'}"&gt;
      &lt;ng-template let-col let-data="rowData" pTemplate="editor"&gt;
              &lt;p-dropdown [(ngModel)]="data[col.field]" [autoWidth]="false" required="true" [options]="attributeOptionList" class="form-control" [style]="{'width':'100%','height':'32px'}"
          filter="filter" placeholder="Select Attribute"&gt;&lt;/p-dropdown&gt;
      &lt;/ng-template&gt;
  &lt;/p-column&gt;
  </code></pre>
  
  <p>Example:
  Dropdown Example</p>
  
  <p><strong>value</strong> | <strong>label</strong></p>
  
  <p>1        |    Newyork</p>
  
  <p>2        |   Auli</p>
  
  <p>On the selection of city id 1, Newyork (label) should be displayed there, not its value. Currently its displaying 1 instead of Newyork</p>