supervisor runs make instead of index.js

no need for verbose child_process code in index.js, just use make to
guarantee `make test` has run before the server is started up again
tiny handwritten static server instead of Connect

Connect isn't super heavyweight, but it and all its dependencies can be
replaced by this tiny thing

it's under script/, instead of having index.js polluting the top level
don't expose entire filesystem to the world

it's a not a huge deal since the server is only exposed to the local
network, and you can specify HOST=localhost to restrict to only your
computer, but still, it's pretty dumb to make it possible for anyone at
all to read your /etc/passwd with http://localhost:9292//etc/passwd

[path.normalize][] fixes this, collapsing multiple slashes and any
directory followed by ../, plus removing all leading /../'s (so no
http://localhost:9292/../../../../../etc/passwd funny business)

[path.normalize]: http://nodejs.org/api/path.html#path_path_normalize_p
log requests, like Connect's static file server

even better, because it has a timestamp on the request
if err, 404 or 500 instead of 200-ing a blank response
Merge pull request #189 from mathquill/build.simplify-server

tiny handwritten static server instead of Connect