update README to demonstrate basic_auth usage

* example didn't work without explicitly setting up authentication.

Author: stevenpollack

README.rst

@@ -24,8 +24,8 @@ Example Usage
 
 .. code:: python
 
-    from neo4j.v1 import GraphDatabase
-    driver = GraphDatabase.driver("bolt://localhost")
+    from neo4j.v1 import GraphDatabase, basic_auth
+    driver = GraphDatabase.driver("bolt://localhost", auth=basic_auth("neo4j", "neo4j"))
     session = driver.session()
     session.run("CREATE (a:Person {name:'Bob'})")
     result = session.run("MATCH (a:Person) RETURN a.name AS name")