Updated README code

All the sample code had source code of:

```php
<?php

require 'api/fitbitphp.php'

$fitbit = new FitBitPHP("57521d64c4044becab73bfc5f2e6578e", "a5b63f9b6e9c4601893dae54c87ab78c");

$fitbit->initSession('http://example.com/callback.php');
$xml = $fitbit->getProfile();

print_r($xml);
?>
```

There needs to be a semi-colon at the end of the require call.
```php
require 'api/fitbitphp.php';
```