Remove fping plugin from V3 API

The fping extension, was introduced in
I7d942270aa52bd6216eda0d7ae366ef0195d52a8.  But this doesn't seem like a
good for nova-api.  We have no other 'instance monitoring' support in
nova and doing it out of the nova-api doesn't seem like the right place.

Change-Id: I3e9bd9b1c04aa06b62f1d3d82b0966e69829a620
Merge "Remove fping plugin from V3 API"