[spec tools] spec tools should be checked into the csswg repo

During the F2F, the use of Tab's preprocessor, bikeshed, was discussed:
http://lists.w3.org/Archives/Public/www-style/2013Sep/0469.html

I think if we're going to switch to using this that we should use a copy
that is checked into the csswg hg repo, along with a copy of the biblio.ref
references file.  That makes life simpler for pulling all needed resources
at the same time and makes it easier for editors in the group to make
changes to the source of the preprocessor, rather than relying on tab
for this.

Cheers,

John Daggett