libvirtd provides was removed from centos7.1

the libvirtd package "Provides" wwas removed from the libvirt packaging.
To workaround this problem just install libvirt-daemon in CentOS 7.1 or Fedora
20+.

WIthout this change, an install of libvirtd does not actually install
libvirtd.  The yum tool will not fail if libvirtd is specified so we weren't
catching this in the build.

Change-Id: I81e64f6f659aa0466369dad4b0574ebb24c99555

docker/nova-compute/nova-libvirt/Dockerfile

 FROM %%KOLLA_NAMESPACE%%/%%KOLLA_PREFIX%%base
 MAINTAINER Kolla Project (https://launchpad.net/kolla)
 
-RUN yum -y install libvirtd libguestfs qemu-system-x86 \
+RUN yum -y install libvirt-daemon \
+        libguestfs \
+        qemu-system-x86 \
         libvirt-daemon-driver-nwfilter \
         libvirt-daemon-config-nwfilter \
         libvirt-daemon-driver-lxc \