Flattened response of wp.getTaxonomies.

If a caller already knows the name of the taxonomy, they can use wp.getTaxonomy to get its data.
Otherwise, a caller can just look at the 'name' field of each taxonomy in the flat response array.

class-wp-xmlrpc-server-ext.php

@@ -1365,7 +1365,7 @@ function wp_getTaxonomies($args) {
 			if ( ! current_user_can( $taxonomy->cap->edit_terms ) )
 				continue;
 
-			$struct[$taxonomy->name] = $this->prepare_taxonomy( $taxonomy );
+			$struct[] = $this->prepare_taxonomy( $taxonomy );
 		}
 
 		return $struct;