Fix the way Apache site configuration files are used, to improve OS portability

On Ubuntu 14.04, the site configuration file must have a .conf suffix for a2ensite and a2dissite to
recognise it. a2ensite and a2dissite ignore the .conf suffix used as parameter. The default sites'
files are 000-default.conf and default-ssl.conf.

On Ubuntu 12.04, the site configuration file may have any format, as long as it is in
/etc/apache2/sites-available/. a2ensite and a2dissite need the entire file name to work. The default
sites' files are default and default-ssl.

On Fedora, any file in /etc/httpd/conf.d/ whose name ends with .conf is enabled.

On RHEL and CentOS, things should hopefully work as in Fedora.

This change puts all distribution-related site configuration file name differences in lib/apache and
the other services gets the file name for its sites using the new exported function
apache_site_config_for <sitename>.

It also makes Fedora disabled sites use the .conf.disabled suffix instead of removing the .conf from
the file name.

The table below summarizes what should happen on each distribution:
+----------------------+--------------------+--------------------------+--------------------------+
| Distribution         | File name          | Site enabling command    | Site disabling command   |
+----------------------+--------------------+--------------------------+--------------------------+
| Ubuntu 12.04         | site               | a2ensite site            | a2dissite site           |
| Ubuntu 14.04         | site.conf          | a2ensite site            | a2dissite site           |
| Fedora, RHEL, CentOS | site.conf.disabled | mv site.conf{.disabled,} | mv site.conf{,.disabled} |
+----------------------+--------------------+--------------------------+--------------------------+

Change-Id: Ia2ba3cb7caccb6e9b65380f9d51d9d21180b894e
Closes-bug: #1313765
diff --git a/lib/neutron_thirdparty/trema b/lib/neutron_thirdparty/trema
index f829aa8..3e59ef2 100644
--- a/lib/neutron_thirdparty/trema
+++ b/lib/neutron_thirdparty/trema
@@ -28,7 +28,7 @@
 TREMA_LOG_LEVEL=${TREMA_LOG_LEVEL:-info}
 
 TREMA_SS_CONFIG=$TREMA_SS_ETC_DIR/sliceable.conf
-TREMA_SS_APACHE_CONFIG=/etc/apache2/sites-available/sliceable_switch.conf
+TREMA_SS_APACHE_CONFIG=$(apache_site_config_for sliceable_switch)
 
 # configure_trema - Set config files, create data dirs, etc
 function configure_trema {
@@ -61,8 +61,9 @@
     sudo cp $TREMA_SS_DIR/apache/sliceable_switch $TREMA_SS_APACHE_CONFIG
     sudo sed -i -e "s|/home/sliceable_switch/script|$TREMA_SS_SCRIPT_DIR|" \
         $TREMA_SS_APACHE_CONFIG
+    # TODO(gabriel-bezerra): use some function from lib/apache to enable these modules
     sudo a2enmod rewrite actions
-    sudo a2ensite sliceable_switch.conf
+    enable_apache_site sliceable_switch
 
     cp $TREMA_SS_DIR/sliceable_switch_null.conf $TREMA_SS_CONFIG
     sed -i -e "s|^\$apps_dir.*$|\$apps_dir = \"$TREMA_DIR/apps\"|" \
@@ -98,8 +99,7 @@
 }
 
 function start_trema {
-    # APACHE_NAME is defined in init_horizon (in lib/horizon)
-    restart_service $APACHE_NAME
+    restart_apache_server
 
     sudo LOGGING_LEVEL=$TREMA_LOG_LEVEL TREMA_TMP=$TREMA_TMP_DIR \
         trema run -d -c $TREMA_SS_CONFIG