Add pear modules, mail and net_smtp via composer (#93)

Add pear modules, mail and net_smtp via composer, remove php 5.6 build due to phpunit 6

lib/composer/vendor/symfony/console/Helper/DescriptorHelper.php

@@ -31,9 +31,6 @@ class DescriptorHelper extends Helper
      */
     private $descriptors = array();
 
-    /**
-     * Constructor.
-     */
     public function __construct()
     {
         $this
@@ -78,7 +75,7 @@ class DescriptorHelper extends Helper
      * @param string              $format
      * @param DescriptorInterface $descriptor
      *
-     * @return DescriptorHelper
+     * @return $this
      */
     public function register($format, DescriptorInterface $descriptor)
     {