Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/imagify/inc/3rd-party/hosting/pressable.php

@@ -0,0 +1,24 @@
+<?php
+defined( 'ABSPATH' ) || die( 'Cheatin’ uh?' );
+
+if ( defined( 'IS_PRESSABLE' ) ) :
+
+	add_filter( 'imagify_site_root', 'imagify_pressable_site_root', IMAGIFY_INT_MAX );
+	/**
+	 * Filter the path to the site's root.
+	 *
+	 * @since  1.9.4
+	 * @author Grégory Viguier
+	 *
+	 * @param  string|null $root_path Path to the site's root. Default is null.
+	 * @return string
+	 */
+	function imagify_pressable_site_root( $root_path ) {
+		$upload_basedir = trim( wp_normalize_path( WP_CONTENT_DIR ), '/' );
+		$upload_basedir = explode( '/', $upload_basedir );
+		$upload_basedir = reset( $upload_basedir );
+
+		return '/' . $upload_basedir . '/';
+	}
+
+endif;