[webui] add release repository button (FATE #315250)
[dist] remove dead code
[dist] escape macros in comments

Macros are evaluated even in comments.
While this instances does not cause any visible errors, it is safer to
properly escape them.
[dist] Explain how sources are retrieved
[dist] Fedora use different user:group for Apache
[dist] test if user and group exist before trying to add