correcting problems with outoloading in composer.json

The autoloading is fixed.

Using the following:


```
   "autoload": {
          "psr-0": {
            "ApnsPHP": "vendor"
        }
   }

```

gennerates this in 'autoloader_namespaces.php' by Composer;


```
   'ApnsPHP' => array($vendorDir . '/varavan/apns-php/vendor'),
```

Changing 'vendor' into '' should fix it


```
   "autoload": {
          "psr-0": {
            "ApnsPHP": ""
        }
   }

```