Change calls to SNAPS library exposing OpenStack instance objects.

Change calls to SNAPS library exposing OpenStack instance objects.

Openstack object structures can change when new API versions are released and
SNAPS no longer is exposing OpenStack object implementations as this makes
the library brittle. The only two SNAPS method calls affected are when functest
needs to query for external networks and when vPing Userdata needs to obtain
the console logs.

JIRA: SNAPS-125

Change-Id: If6000e50eaa274713d9a6c964eabd1f73ded684e
Signed-off-by: spisarski <s.pisarski@cablelabs.com>