Bump 4.4 branch to version 4.4.15

Built from https://develop.svn.wordpress.org/branches/4.4@42938


git-svn-id: http://core.svn.wordpress.org/branches/4.4@42768 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/about.php

@@ -50,6 +50,9 @@ include( ABSPATH . 'wp-admin/admin-header.php' );
 
 		<div class="changelog point-releases">
 			<h3><?php _e( 'Maintenance and Security Releases' ); ?> </h3>
+			<p><?php printf( __( '<strong>Version %s</strong> addressed some security issues.' ), '4.4.15' ); ?>
+				<?php printf( __( 'For more information, see <a href="%s">the release notes</a>.' ), 'https://codex.wordpress.org/Version_4.4.15' ); ?>
+			</p>
 			<p><?php printf( __( '<strong>Version %s</strong> addressed one security issue.' ), '4.4.14' ); ?>
 				<?php printf( __( 'For more information, see <a href="%s">the release notes</a>.' ), 'https://codex.wordpress.org/Version_4.4.14' ); ?>
 			</p>

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4.14';
+$wp_version = '4.4.15';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.