Add PHP 5.5 to travis build
Add PHP 5.5 to travis build

dominionenterprises/mongo-queue-php,nubs/mongo-queue-php,daniel-sc/mongo-queue-php,nubs/mongo-queue-php,dominionenterprises/mongo-queue-php,chadicus/mongo-queue-php,chadicus/mongo-queue-php,daniel-sc/mongo-queue-php