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 '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.