Backport CI service refactoring from EE

It allows easier contribution of different CI services

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix haml indent

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add org-ruby for rendering .org files.
Link to installation page.
Merge branch 'backport-ci-service' into 'master'

Backport CI service refactoring from EE

It allows easier contribution of different CI services.
Fixes #1280
Merge branch 'link-to-installation-options' into 'master'

Link to installation options
Merge branch 'render_org_files' into 'master'

Render org files

Fixes #1215