* Package ./node_modules/* that have a valid license, and since there is already
  a good reason to DFSG-repackage, exclude them from tarball using
  DEB_UPSTREAM_REPACKAGE_EXCLUDES in debian/rules.
  + modules not from upstream author are already dependencies and excluded,
  + modules from upstream author and having a valid license are listed in
    debian/copyright.
* Some of those dependencies are not direct, for example node-block-stream is
  needed by node-tar, but not directly by npm.
* Generate html and man pages from ronnjs. Exclude them too.
  + nodejs >= 0.6.12 ships node-marked. Check if npm will use that tool.
