T/nginx optimization

Adds the following:

 * support for multiple php-fpm pools on a single instance
 * support for the same in nginx
 * shorter timeouts between nginx and php-fpm
 * nginx settings like epoll, more worker connections, auto-select of available cores and accept multiple
 * tests for the pool configuration and setup

Why `node[docroot]` and not `deploy['document_root']`?