Wait for end of copy until spawning tunnel

Fixes the 'spawn ETXTBSY' errors as reported in browserstack#209.
The patch is inspired from browserstack/browserstack-local-nodejs#19 (comment).

Author: Acconut

lib/local.js

@@ -185,12 +185,12 @@ var Tunnel = function Tunnel(key, port, uniqueIdentifier, config, callback) {
     function(response) {
       response.pipe(file);
 
-      response.on('end', function() {
+      file.on('close', function() {
         fs.chmodSync(localBinary, 0700);
-        setTimeout(function() {
-          tunnelLauncher();
-        }, 100);
-      }).on('error', function(e) {
+        tunnelLauncher();
+      });
+
+      response.on('error', function(e) {
         logger.info('Got error while downloading binary: ' + e.message);
         throw new Error('Got error while downloading binary: ' + e.message);
       });