Created new tech-blog post.

About Authorize.ent giving me crap when trying to have a free and non
free set of lineitems and not formatting the 0 in the free one as 0.00,
even though Authorize excepts the 0 for a single item that's not a line
item.

does it make sense? no. Should it? yeah. But as all things on the
internet. We deal with it as it comes.
Added Authorize.net free line item blog post (compile)