adapted tests

I adapted the tests for the last changes. Some explanations : 

* No more need to add the `array('graph')` when sending a Cypher query, it is automatically handled internally now
* The response you will received from the client is automatically guessed, meaning : 

- if the response contains graph results (nodes and relationships), you'll receive automatically a Result object, so no need to do getResult() anymore, just $result = $client->sendCypherQuery($q,.....);

- if there are no graph results, but there are rows results, then you'll receive a Rows array containing key => value pairs from the `rows` section of the neo4j rest api

- If there are no graph results and no rows results, then you receive the array response ;-)

* I adapted a test and added a comment, because you try to match a user in the db but delete the content of the db after each test method with the `setUp()` so it could not work