Change httpd-host type to string/local/nil.

make-network-process requires host name as string or IP address or
symbol "local" as :host parameter. Allowing string makes it easier to
pass non-nil host names.
Adding test dep on 'cl package.

Without this dep tests won't work in batch mode - "flet" is undefined.
Helper function to serve a given directory.
Fix unit tests for name normalization (8ac392e).
Drop all uses of old setq.