Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 0d7960cbb9d4f7f05f8378c8871ddf13e51c8255
  - Enable Airship jobs

    Swift testing and vping_ssh seems good vs CNTT.
    CNTT RI needs to be updated to fully pass swift testing [1][2][3].

    Airship sometimes failed vs vping_ssh because DHCP responds are far
    too long.

    [1] https://jira.opnfv.org/browse/AIRSHIP-39
    [2] https://jira.opnfv.org/browse/AIRSHIP-40
    [3] https://jira.opnfv.org/browse/AIRSHIP-41

    Change-Id: I84a46d14f8c9e7c78f3a6a1e8452114030dcf997
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>