os-vif: add test for versioned object fingerprints
os-vif: add test for versioned object fingerprints

Validate that versioned objects don't get changed without bumping
the version by adding a test for the object fingerprints

NB, until os-vif gets its first release, it is still valid to
change fields without bumping the version.

Change-Id: I9d68d8c9f2be622c03fa6b51b88b0721ab00dca7

openstack/os-vif