Watcher class namespace fix

Use of unqualified name `stdClass` in the `watcher` class caused `SplClassLoader` to look for `stdClass` in `PatternLab` (the current namespace), requiring `builder/lib/PatternLab/stdClass.php`, which doesn't exist and triggers a warning. 

```
PHP Warning:  require(~/patternlab-php/builder/lib/PatternLab/stdClass.php): failed to open stream: No such file or directory in ~/patternlab-php/builder/lib/SplClassLoader.php on line 133
PHP Stack trace:
PHP   1. {main}() ~/patternlab-php/builder/builder.php:0
PHP   2. PatternLab\Watcher->watch() ~/patternlab-php/builder/builder.php:83
PHP   3. SplClassLoader->loadClass() ~/patternlab-php/builder/builder.php:0
PHP Fatal error:  require(): Failed opening required '~/patternlab-php/builder/lib/PatternLab/stdClass.php' (include_path='.:/usr/local/php5/lib/php') in ~/patternlab-php/builder/lib/SplClassLoader.php on line 133
PHP Stack trace:
PHP   1. {main}() ~/patternlab-php/builder/builder.php:0
PHP   2. PatternLab\Watcher->watch() ~/patternlab-php/builder/builder.php:83
PHP   3. SplClassLoader->loadClass() ~/patternlab-php/builder/builder.php:0
```
I simply replaced the unqualified name with the fully qualified name, `\stdClass`, to reference the global class in the global namespace. No more warning.

I also changed the Pascal case of 'StdClass' to camel case on line 44 to match the other lines. Since classnames are not case sensitive, this is of little or no consequence.