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/pear/net_smtp/tests/auth.phpt

@@ -0,0 +1,28 @@
+--TEST--
+Net_SMTP: SMTP Authentication
+--SKIPIF--
+<?php if (!@include('config.php')) die("skip\n");
+--FILE--
+<?php
+
+require_once 'Net/SMTP.php';
+require_once 'config.php';
+
+if (! ($smtp = new Net_SMTP(TEST_HOSTNAME, TEST_PORT, TEST_LOCALHOST))) {
+	die("Unable to instantiate Net_SMTP object\n");
+}
+
+if (PEAR::isError($e = $smtp->connect())) {
+	die($e->getMessage() . "\n");
+}
+
+if (PEAR::isError($e = $smtp->auth(TEST_AUTH_USER, TEST_AUTH_PASS))) {
+	die("Authentication failure\n");
+}
+
+$smtp->disconnect();
+
+echo 'Success!';
+
+--EXPECT--
+Success!