title: How to format data before displaying it on ag-grid
body: <p>I've just discovered <a href="https://github.com/ag-grid/ag-grid-angular" rel="noreferrer">ag-grid</a>. I'm using it on angular2+ and loading data from api. One of fields is date, but its in ISO format. I've been trying to format it, is there any way to do it, is it possible to add pipe or some other way? Usually i do it like this {{ someISODate | date: 'dd.MM.yyyy HH:mm'}}. Do i really have to format it manually in component before displaying it? Also I was wondering if its possible to add two fields under one column. Why? Well i have column author, and in data that im getting from api i have author.firstname and author.lastname, and now I wanna display both fields in same column. Any hints or examples are more than welcomed.</p>
  
  <pre><code>columnDefs = [
      {headerName: 'Datum kreiranja', field: 'createdAt' }, //&lt;-- wanna format it
      {headerName: 'Vrsta predmeta', field: 'type.name' },
      {headerName: 'Opis', field: 'description'},
      {headerName: 'Kontakt', field: 'client.name'},
      {headerName: 'Autor', field: 'author.firstname'}, //&lt;-- wanna display author.lastname in same cell
      {headerName: 'Status', field: 'status.name'}
  ];
  </code></pre>