Expose internal config parameters for starting Ray (#3246)

## What do these changes do?

This PR exposes the CL option for using a config parameter. This is important for certain tests (i.e., FT tests that removing nodes) to run quickly.

Note that this is bad practice and should be replaced with GFLAGS or some equivalent as soon as possible.

#3239 depends on this.

TODO:
 - [x] Add documentation to method arguments before merging.
 - [x] Add test to verify this works?

## Related issue number

python/ray/scripts/scripts.py

@@ -193,13 +193,19 @@ def cli(logging_level, logging_format):
     "--temp-dir",
     default=None,
     help="manually specify the root temporary dir of the Ray process")
+@click.option(
+    "--internal-config",
+    default=None,
+    type=str,
+    help="Do NOT use this. This is for debugging/development purposes ONLY.")
 def start(node_ip_address, redis_address, redis_port, num_redis_shards,
           redis_max_clients, redis_password, redis_shard_ports,
           object_manager_port, node_manager_port, object_store_memory,
           num_workers, num_cpus, num_gpus, resources, head, no_ui, block,
           plasma_directory, huge_pages, autoscaling_config,
           no_redirect_worker_output, no_redirect_output,
-          plasma_store_socket_name, raylet_socket_name, temp_dir):
+          plasma_store_socket_name, raylet_socket_name, temp_dir,
+          internal_config):
     # Convert hostnames to numerical IP address.
     if node_ip_address is not None:
         node_ip_address = services.address_to_ip(node_ip_address)
@@ -269,7 +275,8 @@ def start(node_ip_address, redis_address, redis_port, num_redis_shards,
             autoscaling_config=autoscaling_config,
             plasma_store_socket_name=plasma_store_socket_name,
             raylet_socket_name=raylet_socket_name,
-            temp_dir=temp_dir)
+            temp_dir=temp_dir,
+            _internal_config=internal_config)
         logger.info(address_info)
         logger.info(
             "\nStarted Ray on this node. You can add additional nodes to "
@@ -348,7 +355,8 @@ def start(node_ip_address, redis_address, redis_port, num_redis_shards,
             huge_pages=huge_pages,
             plasma_store_socket_name=plasma_store_socket_name,
             raylet_socket_name=raylet_socket_name,
-            temp_dir=temp_dir)
+            temp_dir=temp_dir,
+            _internal_config=internal_config)
         logger.info(address_info)
         logger.info("\nStarted Ray on this node. If you wish to terminate the "
                     "processes that have been started, run\n\n"