title: Issue in yii2 timezone formatter
body: <p>in php.ini timezone is UTC. system timezone is UTC. yii defaultTimeZone is UTC. But my datetime attribute gets converted to my timezone "Asia/Kolkata" before saving into db.</p>
  
  <p>Eg: UTC time 12:00Hrs
  my input 17.30hrs
  what I expect in db is 12:00hrs and in view 17.30hrs
  But what I got in db is 17:30hrs and in view I got 23:00hrs.</p>
  
  <p>web.php:</p>
  
  <pre><code>'formatter' =&gt; 
          [
              'class' =&gt; 'yii\i18n\Formatter',
              'dateFormat' =&gt; 'php:d-m-Y',
              'datetimeFormat' =&gt; 'php:d-m-Y H:i a',
              'timeFormat' =&gt; 'php:H:i A',
              'timeZone' =&gt; 'Asia/Kolkata',
          ],
  </code></pre>