replace animation public files with a submodule

I bet that submodules are a terrible idea, but no better way to learn
why than to try them myself. I've put the animations in public so that
each page can stand alone and the corresponding css assets can be
served. Theorietically if I do it right I'll just need to merge in new
changes to the submodule to update the blog.
create page that links to the css3_animations submodle

this approach is pretty horrible, but at least it's a first pass. I
don't like the idea of tailoring the directory structure of the
animations repo in order to fit with the blog, but in order to serve the
css assets correctly I need to update the path in the <link>

by reading in the html file and searching for + updating the path, then
serving the updated html, this gets the job done but my god is it ugly
and vulnerable.
just point to the static files

all of the hoops I jumped through revolved around the idea of serving
the animations through a sinatra path when they were all contained in
the public directory. I'd like for all of these files to not sit in the
public directory and to use a cleaner route structue but there isn't a
reason for them not to be there.
pull in changes to css3-animations

I updated the directory structure for the animations repo to isolate the
animations from any other files, and so the glob code that pulls them
needed an update.