docs: function unpackTgz(package_tgz, unpackTarget) {
      return Q.promise(function(resolve, reject) {
          var extractOpts = { type: 'Directory', path: unpackTarget, strip: 1 };
  
          fs.createReadStream(package_tgz)
          .on('error', function (err) {
              events.emit('warn', 'Unable to open tarball ' + package_tgz + ': ' + err);
              reject(err);
          })
          .pipe(zlib.createUnzip())
          .on('error', function (err) {
              events.emit('warn', 'Error during unzip for ' + package_tgz + ': ' + err);
              reject(err);
          })
          .pipe(tar.Extract(extractOpts))
          .on('error', function(err) {
              events.emit('warn', 'Error during untar for ' + package_tgz + ': ' + err);
              reject(err);
          })
          .on('end', resolve);
      })
      .then(function() {
          return unpackTarget;
      });
  }