code: function sortDependencies(plugins) {
      var byTypes = plugins.groupBy(pluginType);
  
      return byTypes.get(TYPE_PLUGIN, Immutable.List())
          .concat(byTypes.get(TYPE_THEME, Immutable.List()));
  }
docs: Sort the list of dependencies to match list in book.json
  The themes should always be loaded after the plugins
  
  @param {List<PluginDependency>} deps
  @return {List<PluginDependency>}