Grab the Everyman folder from https://github.com/jadell/neo4jphp/tree/master/lib and put it into vendor/neo4j/lib
In /app/autoload.php in the $loader->registerNamespaces method, add :
'Everyman' => __DIR__.'/../vendor/neo4j/lib',
to the array argument.
Then you can call the Everyman/Neo4j classes with:
$neo = new \Everyman\Neo4j\Client();
or
use Everyman\Neo4j;
...
$neo = new Neo4j\Client();