lib:npm_registry: initial checkin

lib:npm_registry: initial checkin

Helper module to:

- generate meta information from package.json content.  This data has
  a format as provided by https://registry.npmjs.org

- put this meta information and the corresponding tarball in the
  nodejs cache.  This uses an external, nodejs version specific helper
  script (oe-npm-cache) shipped in oe-meta

To avoid further nodejs version dependencies, future versions of this
module might omit the caching completely and serve meta information
and tarball by an http server.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>