Use name() instead of hand quoting sequence names.

By using name() we can easily accomodate postgres sequences that exist
out side of sequences.

Fixes #4168

lib/Cake/Model/Datasource/Database/Postgres.php

@@ -353,8 +353,8 @@ public function truncate($table, $reset = false) {
 		if ($this->execute('DELETE FROM ' . $this->fullTableName($table))) {
 			if (isset($this->_sequenceMap[$table]) && $reset != true) {
 				foreach ($this->_sequenceMap[$table] as $sequence) {
-					list($schema, $sequence) = explode('.', $sequence);
-					$this->_execute("ALTER SEQUENCE \"{$schema}\".\"{$sequence}\" RESTART WITH 1");
+					$quoted = $this->name($sequence);
+					$this->_execute("ALTER SEQUENCE {$sequence} RESTART WITH 1");
 				}
 			}
 			return true;