Add Fedora 27 support

Removing the (f23,)f24 support they are EOL.
The only non-trivial change is the apache-httpd default worker change,
however might not be bad idea to use `event` instead of `worker`
in the future, but for now keep it AS-IS and continue to use `worker`.

Change-Id: I96d414a30b58bc4b43da45066fdf310a6a830079
Closes-Bug: #1740194
diff --git a/files/rpms/nova b/files/rpms/nova
index 64ed480..9fb7282 100644
--- a/files/rpms/nova
+++ b/files/rpms/nova
@@ -7,7 +7,7 @@
 genisoimage # required for config_drive
 iptables
 iputils
-kernel-modules # dist:f23,f24,f25,f26
+kernel-modules # dist:f25,f26,f27
 kpartx
 libxml2-python
 m2crypto