Allow icinga smokey features to specify notes_url
Allow icinga smokey features to specify notes_url

This allows check_feature to specify an optional notes_url with more
information about the alert. The code to do that is already in
icinga::check, this is just a passthrough of the parameter.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet