Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Fixes missing CephClientKey generation

    In newer OOO deployments, the keys for ceph are dynamically generated.

    Also removes tacker client patch for symmetrical as it is already
    present in stable/pike:
    https://github.com/openstack/python-tackerclient/commit/682c9651085214a58434ad6016d93b2cdc8f3462

    JIRA: APEX-563

    Change-Id: I01fb617b026bae5d6e265a4afbac270939627c5a
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index e1eda22..50f1d92 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit e1eda223437eed7bef2bdfa7bef990a6749f1670
+Subproject commit 50f1d92e0aa0e5720adc44f23ed59a4cfc1c4b58