title: DatePicker issue in yii2
body: <p>Hello I have installed date time picker from "<a href="https://github.com/2amigos/yii2-date-time-picker-widget" rel="nofollow">https://github.com/2amigos/yii2-date-time-picker-widget</a>"</p>
  
  <p>I have put this into vendor/amigos/yii2-date-time-picker-widget-master</p>
  
  <p>I have added following lines in my composer.json
  "amigos/yii2-date-time-picker-widget" : "*" in require section </p>
  
  <p>so it is finally </p>
  
  <pre><code>"require": {
      "php": "&gt;=5.4.0",
      "yiisoft/yii2": "*",
      "yiisoft/yii2-bootstrap": "*",
      "yiisoft/yii2-swiftmailer": "*",
      "amigos/yii2-date-time-picker-widget" : "*"
    },
  </code></pre>
  
  <p>but when I write following code,</p>
  
  <pre><code>&lt;?= DateTimePicker::widget([
  
      'attribute' =&gt; 'created_at',
      'language' =&gt; 'es',
      'size' =&gt; 'ms',
      'clientOptions' =&gt; [
          'autoclose' =&gt; true,
          'format' =&gt; 'dd MM yyyy - HH:ii P',
          'todayBtn' =&gt; true
      ] ]);?&gt;
  </code></pre>
  
  <p>It says "Class 'DateTimePicker' not found"</p>