Fix spurious 'unsafe include' errors and rpmlint complaints
    - Use 'unsafe' mode by default (bug 506953)
    - Install filter scripts in %{_datadir}/asciidoc
    - Convert spec file, CHANGELOG, and README to utf-8
    - Preserve timestamps on installed files, where feasible
    - s/$RPM_BUILD_ROOT/%{buildroot} and drop duplicated /'s
    - Fix rpmlint mixed-use-of-spaces-and-tabs and end-of-line-encoding
        warnings