Added mod returning a list of known hubs, for a lightweight hub crawler

mod/knownhubs.php

@@ -0,0 +1,22 @@
+<?php
+
+function knownhubs_init(&$a) {
+
+	if ($a->argv[1]=="json"){
+		$known_hubs = array();
+		$r = q("SELECT s.site_url FROM site as s group by s.site_url");
+
+		if(count($r)) {
+			foreach($r as $rr) {
+				$known_hubs[] = $rr['site_url'];
+			}
+		}
+		sort($known_hubs);
+		
+		$data = Array(
+			'knownhubs' => $known_hubs,
+		);
+		json_return_and_die($data);
+	}
+	
+}