Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Replace CONST.* by getattribute/setattr for refstack"
  - Replace CONST.* by getattribute/setattr for refstack

    Directories affected:
     - functest/opnfv_tests/openstack/refstack_client
    and respective unit test

    JIRA: FUNCTEST-796

    Change-Id: I7f7047d44d71e82bcc1f66ec0b760ff30a13dbd5
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 3c8f13c..d4ccab3 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 3c8f13cc1c832ec08fde0a3b502fe688f4597259
+Subproject commit d4ccab3e956166787dc140b64b5b2a96669aa93b