ishmael - include ::apache::mod::headers

the Apache hosting ishmael, running on neon
along with icinga, needs mod_headers for
Id90f77b8c07 to work and redirect http->https

just like I5a3032eb907a

icinga did not require this or we would have loaded
it already

Change-Id: Ided5b65aae1fd565dae0a96b02d1c4eb51b4b863
Merge "ishmael - include ::apache::mod::headers" into production