docs: function getAvailableNpmVersions(module_name) {
      var npm = require('npm');
      return Q.nfcall(npm.load).then(function () {
          return Q.ninvoke(npm.commands, 'view', [module_name, 'versions'], /* silent = */ true).then(function (result) {
              // result is an object in the form:
              //     {'<version>': {versions: ['1.2.3', '1.2.4', ...]}}
              // (where <version> is the latest version)
              return result[Object.keys(result)[0]].versions;
          });
      });
  }