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/consolidation/robo/robo

@@ -17,5 +17,6 @@ if (strpos(basename(__FILE__), 'phar')) {
     }
 }
 $runner = new \Robo\Runner();
+$runner->setSelfUpdateRepository('consolidation/robo');
 $statusCode = $runner->execute($_SERVER['argv']);
 exit($statusCode);