Update git submodules

Update git submodules

* Update docs/submodules/compass4nfv from branch 'stable/euphrates'
  - Merge "Add customized DNS server support" into stable/euphrates
  - Add customized DNS server support

    JIRA: -

    Currently Compass uses the gateway of install network as the only
    DNS server of host1 to 5. Sometimes it doesn't work in some
    environments. This patch we add a variable named USER_NAMESERVER
    which can be exported before deployment. It is used to store a
    user defined DNS nameserver.

    Change-Id: Id74889c20cf09ec7e25d882b56ab6331ee64cdcf
    Signed-off-by: Yifei Xue <xueyifei@huawei.com>
    (cherry picked from commit 7b110b32e0688896967703dc2bfe7192d469164f)