title: Laravel Eloquent created_at is getting updated
body: <p>I just hit a snag with Eloquent's (Laravel 5.2.10) default timestamps. By default the <code>$table-&gt;timestamps()</code> method gives you a <code>created_at</code> and an <code>updated_at</code> column in your table which are updated accordingly. </p>
  
  <p>However, when I was trying some test entries, I noticed that when you update a record, the <code>updated_at</code> field gets updated, as it should, but the <code>created_at</code> field <strong>also</strong> gets updated: its hours stays at the created time, but the minutes and seconds get updated to match the <code>updated_at</code> field.</p>
  
  <p>If that was too wordy, here is an example:</p>
  
  <pre><code>+---------------------+---------------------+
  | created_at          | updated_at          |
  +---------------------+---------------------+
  | 2016-01-13 17:13:27 | 2016-01-13 22:13:27 |
  | 2016-01-13 16:14:41 | 2016-01-13 21:14:41 |
  +---------------------+---------------------+
  </code></pre>
  
  <p>Notice that the minutes and seconds are the exact same for the <code>created_at</code> and <code>updated_at</code> field.</p>
  
  <p>I tried to look through the <code>Model</code> class where the timestamps are set, but it turns out the <code>setCreatedAt()</code> method is indeed not called when just updating a record.</p>
  
  <p><strong>Why</strong> does this happen?<br>
  <strong>How</strong> do I prevent the <code>created_at</code> field from changing? (more important)</p>