Fix logic error. Ignore "422 Unprocessable Entity Floating ip" exceptions on destroy_instance.
Fix logic error. Ignore "422 Unprocessable Entity Floating ip" exceptions on destroy_instance.

	modified:   service/instance.py

CCI-MOC/GUI-Backend,CCI-MOC/GUI-Backend,CCI-MOC/GUI-Backend,CCI-MOC/GUI-Backend