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/myclabs/deep-copy/fixtures/f007/FooDateInterval.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace DeepCopy\f007;
+
+use DateInterval;
+
+class FooDateInterval extends DateInterval
+{
+    public $cloned = false;
+
+    public function __clone()
+    {
+        $this->cloned = true;
+    }
+}