Add debug string to raylet (#3317)

* initial debug string

* format

* wip debug string

* fix compile

* fix

* update

* finished

* to file

* logs dir

* use temp root

* fix

* override

python/ray/services.py

@@ -955,6 +955,7 @@ def start_raylet(redis_address,
         start_worker_command,
         "",  # Worker command for Java, not needed for Python.
         redis_password or "",
+        get_temp_root(),
     ]
 
     if use_valgrind:

python/ray/worker.py

@@ -1655,7 +1655,7 @@ def init(redis_address=None,
         driver_id: The ID of driver.
         configure_logging: True if allow the logging cofiguration here.
             Otherwise, the users may want to configure it by their own.
-        logging_level: Logging level, default will be loging.INFO.
+        logging_level: Logging level, default will be logging.INFO.
         logging_format: Logging format, default will be "%(message)s"
             which means only contains the message.
         plasma_store_socket_name (str): If provided, it will specify the socket