Use wp remote fopen instead of file_get_contents

First commit: Removal of all the whitespaces. 

Second commit: You are using file_get_contents to retrieve a remote file. This can cause the following warning to appear:

```
 Warning: file_get_contents(): http:// wrapper is disabled in the server configuration by allow_url_fopen=0 in /var/www/codepress/public/wp-content/plugins/advanced-custom-fields/core/controllers/upgrade.php on line 109 Warning: file_get_contents(http://plugins.svn.wordpress.org/advanced-custom-fields/trunk/readme.txt): failed to open stream: no suitable wrapper could be found in /var/www/codepress/public/wp-content/plugins/advanced-custom-fields/core/controllers/upgrade.php on line 109
```

Fix included, which use wp_remote_fopen().