Restructure and document the local configuration file

Change-Id: I5100a605ec197abf737278941c164b478a31a723

puppet/modules/devstack/templates/local.erb

@@ -1,41 +1,62 @@
 [[local|localrc]]
+
+# generic configuration parameters
+
 DATABASE_PASSWORD=pass
 RABBIT_PASSWORD=pass
 SERVICE_TOKEN=pass
 SERVICE_PASSWORD=pass
 ADMIN_PASSWORD=pass
+
 MULTI_HOST="True"
 API_RATE_LIMIT="False"
 RECLONE="True"
+
+# database configuration parameters
+
+DATABASE_TYPE=mysql
+
+# networking configuration parameters
+
 GUEST_INTERFACE_DEFAULT=eth1
 HOST_IP_IFACE=eth1
 
-# Enable Logging
+# logging configuration parameters
+
 LOGFILE=/opt/stack/logs/stack.sh.log
 VERBOSE=True
 LOG_COLOR=True
 SCREEN_LOGDIR=/opt/stack/logs
 
 <% if @is_compute == "true" %>
+# generic configuration parameters (compute)
+
 ENABLED_SERVICES=n-cpu,n-net,c-vol
-DATABASE_TYPE=mysql
 SERVICE_HOST=<%= @hostname_manager %>
 MYSQL_HOST=$SERVICE_HOST
 RABBIT_HOST=$SERVICE_HOST
 GLANCE_HOST=$SERVICE_HOST
 
+# configure ceilometer (compute)
+
 enable_service ceilometer-acompute
 <% else %>
-# The manager
+
+# configure images provided on glance (manager)
+
 IMAGE_URLS="http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-uec.tar.gz"
 IMAGE_URLS+=",https://download.fedoraproject.org/pub/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2"
 IMAGE_URLS+=",https://cloud-images.ubuntu.com/precise/current/precise-server-cloudimg-amd64-disk1.img"
 
+# configure ceilometer (manager)
+
 enable_service dstat
 enable_service ceilometer-acompute ceilometer-acentral ceilometer-anotification ceilometer-collector ceilometer-api
 enable_service ceilometer-alarm-notifier ceilometer-alarm-evaluator
 
 <% if @use_ldap == "true" %>
+# LDAP configuration parameters (manager)
+
 LDAP_PASSWORD=pass
 enable_service ldap
 <% end %>