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/process/Pipes/WindowsPipes.php

@@ -26,16 +26,12 @@ use Symfony\Component\Process\Exception\RuntimeException;
  */
 class WindowsPipes extends AbstractPipes
 {
-    /** @var array */
     private $files = array();
-    /** @var array */
     private $fileHandles = array();
-    /** @var array */
     private $readBytes = array(
         Process::STDOUT => 0,
         Process::STDERR => 0,
     );
-    /** @var bool */
     private $haveReadSupport;
 
     public function __construct($input, $haveReadSupport)