Correct exception
Correct exception

This change updates the exception call when using the new `vip_file`
argument. Presently there's no CommandError within tripleoclient,
which results in an AttributeError, so we move the call to osc_lib which
has what we're expecting.

Change-Id: I94e00ed3000982c2563c54d73e0c1cfd0ac7c6a3
Signed-off-by: Kevin Carter <1d9a750a4fc7026fb02029431dc8a87d24487135@redhat.com>

openstack/python-tripleoclient