MAW-875: session plugin to must-use

wp/wp-content/mu-plugins/wp-native-php-sessions.php

@@ -0,0 +1,11 @@
+<?php
+/*
+Plugin Name: MU WP Native PHP Sessions
+Plugin URI: https://wordpress.org/plugins/wp-native-php-sessions/
+Description: Building on Pantheon's and WordPress's strengths, together.
+Version: 0.1
+Author: Pantheon
+Author URI: http://getpantheon.com
+*/
+
+require_once( 'wp-native-php-sessions/pantheon-sessions.php' );