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/Tests/Fixtures/DummyOutput.php

@@ -26,7 +26,7 @@ class DummyOutput extends BufferedOutput
     public function getLogs()
     {
         $logs = array();
-        foreach (explode("\n", trim($this->fetch())) as $message) {
+        foreach (explode(PHP_EOL, trim($this->fetch())) as $message) {
             preg_match('/^\[(.*)\] (.*)/', $message, $matches);
             $logs[] = sprintf('%s %s', $matches[1], $matches[2]);
         }