Compatibility with Symfony 3.x and 4.x
Some brush-ups (#1) * Some brush-ups, tweak Travis build matrix, update PHPUnit, drop webfactory/symfony-application-tests dependency * Fix Travis CI config * Tweak the README
Some brush-ups (#1) * Some brush-ups, tweak Travis build matrix, update PHPUnit, drop webfactory/symfony-application-tests dependency * Fix Travis CI config * Tweak the README