SELinux changes for EL7 and CIM

Allow CIM access to libvirt and to read /etc/shadow for auth
checking.

Change-Id: Icb6936202dedd340084dddaf846947acf64119e7
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1120621
Signed-off-by: Ryan Barry <rbarry@redhat.com>