Update composer.json

Hi Anton,
I just installed your orientdb-php package via composer and found it was not autoloading the OrientDB files properly. I added 

"autoload": {
			"files": ["OrientDB/OrientDB.php"]
		}

to the composer.json file (and the installed.json file of composer since composer recreates the autoloader from there) to make it work. I am not sure whether you intentionally left it out and I am just doing it wrong, but nevertheless wanted to let you know that the composer package did not work straight out of the box.

Best regards
Migronon