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/annotated-command/src/Parser/DefaultsWithDescriptions.php

@@ -32,7 +32,9 @@ class DefaultsWithDescriptions
     public function __construct($values = [], $defaultDefault = null)
     {
         $this->values = $values;
-        $this->hasDefault = [];
+        $this->hasDefault = array_filter($this->values, function ($value) {
+            return isset($value);
+        });
         $this->descriptions = [];
         $this->defaultDefault = $defaultDefault;
     }