Better dev dependencies.
Better dev dependencies.

 * Add dependency on php-cs-fixer, since we use it.
 * Add a useful PHPUnit dependency version.
thecocce/mustache.php,irontec/mustache,bobthecow/mustache.php,cgvarela/mustache.php,zuluf/mustache.php,ericariyanto/mustache.php,BrunoDeBarros/mustache.php,evdevgit/mustache.php,sophatvathana/mustache.php