PHP 5.3 compatibility fixes.

Would there be any interest in supporting PHP 5.3?

I would like to use FastRoute as a dependency in an upcoming project but we wish to support PHP 5.3 with the upcoming project. This PR makes mostly syntatic sugar changes for PHP 5.3 compatibility. The full test suite runs just fine on PHP 5.3 (minus the tests that are skipped for PHP 5.4 and 5.5 as well).

Beyond the nice array syntax in PHP 5.4 is any other real reason this project shouldn't support PHP 5.3?