Correctly enable extra collectors (#70)

* Correctly enable extra collectors

[fix]

When collectors have optional params, make sure to also enable the
collector. This fixes adjusting systemd flags because systemd collector
is disabled by default.

* Ignore long lines in ansble-lint

.ansible-lint

+---
+skip_list:
+- '204'

templates/node_exporter.service.j2

@@ -14,6 +14,7 @@ ExecStart=/usr/local/bin/node_exporter \
     --collector.{{ collector }} \
 {%   else -%}
 {%     set name, options = (collector.items()|list)[0] -%}
+    --collector.{{ name }} \
 {%     for k,v in options|dictsort %}
     --collector.{{ name }}.{{ k }}={{ v }} \
 {%     endfor -%}