Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Dynamic region name of juju cloud"
  - Dynamic region name of juju cloud

    Region name in juju cloud has been made dynamic now, region name
    will be added in cloud file from os environment variable.
    It fixes the issues when runnit juju_epc vs Apex [1].

    It also updates ubuntu images to xenial.

    [1] https://build.opnfv.org/ci/job/functest-apex-baremetal-daily-master/628/console

    Change-Id: I9422af3086141cd40b99e6482883a7081f58c2ea
    Signed-off-by: soumaya <soumaya.nayek@rebaca.com>