Set the log directory accordingly

This changes the log directory within the upstart init scripts
such that they are being set throughout the roles and removes an
assumed variable name as the name of the log directory.

Change-Id: I32a2a76a4a73b609999886427b494f380850f12a
Closes-Bug: #1460469

templates/neutron-upstart-init.j2

@@ -38,4 +38,4 @@ exec start-stop-daemon --start \
                        --pidfile /var/run/{{ program_name }}/{{ program_name }}.pid \
                        --exec "{{ program_override|default('$RUNBIN') }}" \
                        -- {{ program_config_options|default('') }} \
-                       --log-file=/var/log/{{ service_name }}/{{ program_name }}.log
+                       --log-file=/var/log/neutron/{{ program_name }}.log