v1.5.0

1. PHP-CS-Fixer bump to ^2.5 (https://github.com/FriendsOfPHP/PHP-CS-Fixer/releases/tag/v2.5.0)
2. Drop custom Slam/no_unneeded_final_method
3. Use new fixers no_superfluous_elseif, no_unneeded_curly_braces and no_unneeded_final_method