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

lib/apache

@@ -133,8 +133,9 @@ function install_apache_wsgi {
         sudo rm -f /etc/httpd/conf.d/000-*
         install_package httpd mod_wsgi
         # For consistency with Ubuntu, switch to the worker mpm, as
-        # the default is prefork
+        # the default is event
         sudo sed -i '/mod_mpm_prefork.so/s/^/#/g' /etc/httpd/conf.modules.d/00-mpm.conf
+        sudo sed -i '/mod_mpm_event.so/s/^/#/g' /etc/httpd/conf.modules.d/00-mpm.conf
         sudo sed -i '/mod_mpm_worker.so/s/^#//g' /etc/httpd/conf.modules.d/00-mpm.conf
     elif is_suse; then
         install_package apache2 apache2-mod_wsgi