Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Add param for ODL password into overcloudrc

    Recent changes upstream have removed the default 'admin' ODL password
    and now password is randomly generated:

    https://review.openstack.org/#/c/578505/

    So in OPNFV we now store the password in overcloudrc as
    SDN_CONTROLLER_PASSWORD variable.

    Also includes minor fixes to unittests.

    Change-Id: Iabe7e4f902442c80af99ba1603a3927cf13d0393
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 6b9d8c0..a473a19 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 6b9d8c01be763bbf46048caa08902880367672a7
+Subproject commit a473a19aca3837eeb77adc41523bb1db95b5f47d