copr-be: handler for restarting node_exporter

roles/copr/backend/handlers/main.yml

@@ -10,3 +10,6 @@
 
 - name: restart lighttpd
   action: service name=lighttpd state=restarted
+
+- name: restart node_exporter
+  action: service name=node_exporter state=restarted

roles/copr/backend/tasks/main.yml

@@ -167,6 +167,7 @@
     path: /etc/sysconfig/node_exporter
     regexp: '^OPTIONS='
     line: 'OPTIONS=--collector.textfile.directory /var/lib/node_exporter/textfile_collector --collector.systemd'
+    backrefs: yes
   notify: restart node_exporter
 
 # setup dirs for the ansible execution off of provisioning