* Change DEB nodejs relation from Depends to Recommends
A "Recommends" relation preserves the out-of-the-box experience for most people,
as recommended packages are installed by default on modern Debian / Ubuntu
distros. But it allows people who install Node.js in a different manner to opt
out of the nodejs DEB package.
* Add "Conflicts" relationship with DEB nodejs < 4.0.0
* Script to build Debian package
* Adjustments for Debian scripts:
- Add copyright file
- Add full description to control file
- Ignore some lintian rules
- Delete clowny files that aren't needed and break lintian rules
- Update shebang in yarn.js from "node" to "nodejs" as per Debian package of Node
* Add basic Debian instructions
* Revert readme change and explicitly require Node.js 4 or above
