Update git submodules

Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Added exception handling around adding security groups.

    When a VM instance has a security group associated with it and
    the client attempts to add the same security group, a Pike pod
    now raises a ClientException where previous releases simply return
    None. This patch adds the appropriate exception handling that
    allows several existing tests to pass not only with Pike but also
    with all OpenStack versions.

    JIRA: SNAPS-239

    Change-Id: I282df5a2b516dab415ba5e2e7208176f2ba3f270
    Signed-off-by: spisarski <s.pisarski@cablelabs.com>