Merge in cl/201712945

Changes to provide base image name for goldfish instance via command
line. It should override the value provided by the configuration.

Bug: None
Test: ./run_tests.sh
Change-Id: I418cef25bddf7fa42e93726401f206aa44e9736f
diff --git a/public/acloud_main.py b/public/acloud_main.py
index 9ff0168..4802bac 100644
--- a/public/acloud_main.py
+++ b/public/acloud_main.py
@@ -317,6 +317,14 @@
         help=
         "For each instance created, we will automatically creates both 2 ssh"
         " tunnels forwarding both adb & vnc. Then add the device to adb.")
+    create_gf_parser.add_argument(
+        "--base_image",
+        type=str,
+        dest="base_image",
+        required=False,
+        help="Name of the goldfish base image to be used to create the instance. "
+        "This will override stable_goldfish_host_image_name from config. "
+        "e.g. emu-dev-cts-061118")
 
     subparser_list.append(create_gf_parser)