Install Nova into its own venv

Install a couple of optional feature prereqs in hypervisor plugins.

rootwrap is horribly called indirectly via PATH.  The choice, other than fixing
such nonsense, is to force the path in sudo.

TODO:
* python guestfs isn't in pypi, need to specifically install it to not
  use the distro package

Change-Id: Iad9a66d8a937fd0b0d1874005588c702e3d75e04

lib/nova_plugins/functions-libvirt

@@ -21,14 +21,16 @@ DEBUG_LIBVIRT=$(trueorfalse False DEBUG_LIBVIRT)
 function install_libvirt {
     if is_ubuntu; then
         install_package qemu-kvm
-        install_package libvirt-bin
-        install_package python-libvirt
-        install_package python-guestfs
+        install_package libvirt-bin libvirt-dev
+        pip_install libvirt-python
+        install_package libguestfs0
+        #install_package python-guestfs
+        #pip_install <there-si-no-guestfs-in-pypi>
     elif is_fedora || is_suse; then
         install_package kvm
-        install_package libvirt
-        install_package libvirt-python
-        install_package python-libguestfs
+        install_package libvirt libvirt-devel
+        pip_install libvirt-python
+        #install_package python-libguestfs
     fi
 
     # Restart firewalld after install of libvirt to avoid a problem