Update Ubuntu packaging for the node.js build system, add debugging symbols

Now the packaging simply runs ./do and grabs the resulting binaries.

It only installs the "cjdroute" binary for now. **Is that correct?** Should any other binaries be included, such as dnsserv?

I've also added a "cjdns-dbg" package that ships debugging symbols, as per Debian convention (the binaries in a regular package are always stripped).