Improved comments, split up role, moved tags and added defaults

- Added some commenting inside of defaults to clarify which variables
  adjust which files

- Split up the role taking items out of main.yml in tasks. This is to
  improve clarity of what each bit of Ansible code is doing.

- Tags were defined for each and every task within the Debian.yml moved
  ths up to main.yml so they don't need repeating every task adding
  clutter.

- Added some extra default plugins, as of current release version these
  are now within the default configuration but were missing from this
  role.

- Added some commenting inside the templates and the top of some tasks
  to clarify where the templated file was coming from.

templates/etc-opt-telegraf-telegraf.conf.j2

@@ -1,4 +1,4 @@
-# Telegraf configuration
+### MANAGED BY {{ role_path|basename }} ANSIBLE ROLE ###
 
 [tags]
 {% if telegraf_global_tags is defined and telegraf_global_tags is iterable %}

templates/telegraf-extra-plugin.conf.j2

@@ -1,3 +1,5 @@
+### MANAGED BY {{ role_path|basename }} ANSIBLE ROLE ###
+
 [[inputs.{{ item.plugin }}]]
 {% if item.interval is defined %}
     interval = "{{ item.interval }}s"

templates/telegraf.conf.j2

@@ -1,4 +1,4 @@
-# Telegraf configuration
+### MANAGED BY {{ role_path|basename }} ANSIBLE ROLE ###
 
 [global_tags]
 {% if telegraf_global_tags is defined and telegraf_global_tags is iterable %}