Rename EOS Heredocs to CSS

Heredocs can be given a useful description, so use `CSS` instead of the
vague `EOS`.

Change-Id: I768496c24fb95567bd18b145e05b3274e417f30b
Reviewed-on: https://gerrit.causes.com/23143
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>