Virt inspector directly layered over hypervisor API

Addresses BP nova-independent-virt

Add the concept of a pluggable virt inspector that allows
polling of the hypervisor layer without relying on any
nova internals.

Note that the test-requires dependency on the nova master
tarball remains in place for the moment, as it's required
by the nova notifier tests.

Also we must leave the dependency on the libvirt-python
RPM or python-libvirt Debian package to the distros which
end up packaging ceilometer.

Change-Id: I20700320dd7e3196507173c780ab598b479e4021

setup.py

@@ -111,10 +111,10 @@ setuptools.setup(
     floatingip = ceilometer.network.notifications:FloatingIP
 
     [ceilometer.poll.compute]
-    libvirt_diskio = ceilometer.compute.libvirt:DiskIOPollster
-    libvirt_cpu = ceilometer.compute.libvirt:CPUPollster
-    libvirt_net = ceilometer.compute.libvirt:NetPollster
-    libvirt_instance = ceilometer.compute.libvirt:InstancePollster
+    diskio = ceilometer.compute.pollsters:DiskIOPollster
+    cpu = ceilometer.compute.pollsters:CPUPollster
+    net = ceilometer.compute.pollsters:NetPollster
+    instance = ceilometer.compute.pollsters:InstancePollster
 
     [ceilometer.poll.central]
     network_floatingip = ceilometer.network.floatingip:FloatingIPPollster
@@ -129,5 +129,8 @@ setuptools.setup(
     postgresql = ceilometer.storage.impl_sqlalchemy:SQLAlchemyStorage
     sqlite = ceilometer.storage.impl_sqlalchemy:SQLAlchemyStorage
     test = ceilometer.storage.impl_test:TestDBStorage
+
+    [ceilometer.compute.virt]
+    libvirt = ceilometer.compute.virt.libvirt.inspector:LibvirtInspector
     """),
     )