Merge pull request #61 from netsgnut/fix-pg-log

Fix 'undefined is not a function' problem at postgres adapter

lib/adapters/postgres.js

@@ -46,7 +46,7 @@ PG.prototype.query = function (sql, callback) {
     var time = Date.now();
     var log = this.log;
     this.client.query(sql, function (err, data) {
-        log(sql, time);
+        if (log) log(sql, time);
         callback(err, data ? data.rows : null);
     });
 };