PHP-1335: Add Collection::findOne() helper
PHP-1335: Add Collection::findOne() helper

mongodb/mongo-php-library,jmikola/mongo-php-library,derickr/mongo-php-library,jmikola/mongo-php-library,jmikola/mongo-php-library,bjori/mongo-php-library-prototype,10gen-labs/mongo-php-library-prototype,mongodb/mongo-php-library,jmikola/mongo-php-library-prototype,mongodb-labs/mongo-php-library-prototype,mongodb/mongo-php-library,derickr/mongo-php-library,Kozzi11/mongo-php-library-prototype,Fiskie/mongo-php-library,derickr/mongo-php-library-prototype,mongodb/mongo-php-library,jmikola/mongo-php-library,jaleelzhang/mongo-php-library-prototype,serebro/mongo-php-library-prototype