Move article styling out of eos-help-center-style.css

We had some article styling in that file, but that belongs in our
separate article-style.css file.
[endlessm/eos-shell#4202]
Make the side list a ol instead of ul

Its an ordered list, so ol is more appropriate
[endlessm/eos-shell#4202]
Remove unused css utilities

I don't think font awesome was being used anywhere, not was
utilities.css.

Also some css files were included from other css files and also
included in through our xslt.

Did all the inclusion trough xslt to be consistent

[endlessm/eos-shell#4202]