REST API: Add gmt_offset and timezone_string to the base /wp-json response.

The site's current timezone offset is an important piece of information for any REST API client that needs to manipulate dates.  It has not been previously available.

Expose both the `gmt_offset` (the site's current offset from UTC in hours) and `timezone_string` (which also provides information about daylight savings time) via the "site info" endpoint (the base `/wp-json` response).

Also update the `wp-api-generated.js` fixture file with the changes to the default API responses.

Props sagarkbhatt.
Fixes #39854.

Built from https://develop.svn.wordpress.org/trunk@40238


git-svn-id: http://core.svn.wordpress.org/trunk@40168 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api/class-wp-rest-server.php

@@ -1012,13 +1012,15 @@ class WP_REST_Server {
 	public function get_index( $request ) {
 		// General site data.
 		$available = array(
-			'name'           => get_option( 'blogname' ),
-			'description'    => get_option( 'blogdescription' ),
-			'url'            => get_option( 'siteurl' ),
-			'home'           => home_url(),
-			'namespaces'     => array_keys( $this->namespaces ),
-			'authentication' => array(),
-			'routes'         => $this->get_data_for_routes( $this->get_routes(), $request['context'] ),
+			'name'            => get_option( 'blogname' ),
+			'description'     => get_option( 'blogdescription' ),
+			'url'             => get_option( 'siteurl' ),
+			'home'            => home_url(),
+			'gmt_offset'      => get_option( 'gmt_offset' ),
+			'timezone_string' => get_option( 'timezone_string' ),
+			'namespaces'      => array_keys( $this->namespaces ),
+			'authentication'  => array(),
+			'routes'          => $this->get_data_for_routes( $this->get_routes(), $request['context'] ),
 		);
 
 		$response = new WP_REST_Response( $available );

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40237';
+$wp_version = '4.8-alpha-40238';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.