server/public/fonts/Font-Awesome: remove .git folder

[#46761159]

When copying resources to server/public make sure that
the .git modulars that deify the original folder as a
git submodule do not end up in server/public.

Not only does it add unnecessarily to the static distribution size
the presence of the .git folder prevents the gh-pages.rb script
from completing when it tries to add the new files to the gh-pages
branch:

$ git add .
fatal: Not a git repository: vendor/fonts/Font-Awesome/../../../../.git/modules/src/vendor/fonts/Font-Awesome

problem introduced in: 643b854d
index.html: use relative url to fonts

[#46761483]

Also fix Guardfile to correctly generate index.css
using updated Sass invocation used in Makefile.
use relative path for fontawesome-webfont request

[#46761677]

To make these requests valid for static distributions in
subdirectories and also when served through a proxy like
DataGames
clarify script/gh-pages.sh error mesg
use global flag in regex to update *all* links

[#45737301], [#46733573]
Markdown: newline needed between para and heading

[#45737301],
Bob's 7 new v24 Airbags models