Adds support for PHP 5.4+ embeddable web server

User simply runs with php -S 0.0.0.0:8000 run.php and app works.
No need for other servers, this is super useful for RPI or testing, developing.

PHP 5.4+ only
Add support for thumbnails
Merge pull request #376 from dz0ny/php-embed-server

Adds support for PHP 5.4+ embeddable web server