Update git submodules

Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Adding tests for IPv6.

    Included in patch:
    1. Refactor Network domain object to include Subnet objects
    2. Removed subnet members from OpenStackNetwork
    3. Added exhausive IPv6 tests to neutron_utils_tests.py
    4. Added two IPv6 integration tests to create_network_tests.py
    5. Added two tests where VM instances have ports with IPv6 addresses
    6. Updated docs

    JIRA: SNAPS-178

    Change-Id: Id3e5448cb431d2acf47029244fe6773f3f29d368
    Signed-off-by: spisarski <s.pisarski@cablelabs.com>