Reverted PHP req to >= 5.3.3
Reverted PHP req to >= 5.3.3

Reverted the requirement of PHP 5.3.4 matching Symfony's revert

kaduev13/event-loop,mkrauser/event-loop,steverhoades/event-loop,kaduev13/event-loop,steverhoades/event-loop,clue-labs/event-loop,reactphp/event-loop,mkrauser/event-loop