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/CommandLoader/CommandLoaderInterface.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Symfony\Component\Console\CommandLoader;
+
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Exception\CommandNotFoundException;
+
+/**
+ * @author Robin Chalas <robin.chalas@gmail.com>
+ */
+interface CommandLoaderInterface
+{
+    /**
+     * Loads a command.
+     *
+     * @param string $name
+     *
+     * @return Command
+     *
+     * @throws CommandNotFoundException
+     */
+    public function get($name);
+
+    /**
+     * Checks if a command exists.
+     *
+     * @param string $name
+     *
+     * @return bool
+     */
+    public function has($name);
+
+    /**
+     * @return string[] All registered command names
+     */
+    public function getNames();
+}