Move Style classes into Common folder (#432)

src/Spout/Writer/CSV/Writer.php

@@ -81,7 +81,7 @@ class Writer extends WriterAbstract
      *
      * @param  array $dataRow Array containing data to be written.
      *          Example $dataRow = ['data1', 1234, null, '', 'data5'];
-     * @param \Box\Spout\Writer\Style\Style $style Ignored here since CSV does not support styling.
+     * @param \Box\Spout\Writer\Common\Entity\Style\Style $style Ignored here since CSV does not support styling.
      * @return void
      * @throws \Box\Spout\Common\Exception\IOException If unable to write data
      */