Expand callbacks in uploader

Functionally no different, but if an async.js error occurs, display these in the stack trace (may make issues easier to identify)

lib/uploader.js

@@ -181,7 +181,9 @@ Uploader.prototype = {
 											self._checkLoop(c, cb)();
 										} else {
 											// no checking needed on this connection, close it down
-											self._closeConnection('post', c.connNum, cb);
+											self._closeConnection('post', c.connNum, function() {
+												cb();
+											});
 										}
 										return;
 									}
@@ -285,7 +287,9 @@ Uploader.prototype = {
 			if(err) return cb(err);
 			self.checkQueue.take(function(post) {
 				if(!post) { // done, close down
-					self._closeConnection('check', c.connNum, cb);
+					self._closeConnection('check', c.connNum, function() {
+						cb();
+					});
 					// TODO: assumes that this is a checking connection and not a posting one
 					return;
 				}