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/f008/A.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace DeepCopy\f008;
+
+class A
+{
+    private $foo;
+
+    public function __construct($foo)
+    {
+        $this->foo = $foo;
+    }
+
+    public function getFoo()
+    {
+        return $this->foo;
+    }
+}