Class inherited from `WPCOMUnpublished` class and adds
specific methods useful for wp-calypso.

@param {String} [token] - oauth token
@param {Function} [reqHandler] - request handler
@return {NUll} null
function WPCOMUndocumented( token, reqHandler ) {
	if ( ! ( this instanceof WPCOMUndocumented ) ) {
		return new WPCOMUndocumented( token, reqHandler );
	}

	if ( 'function' === typeof token ) {
		reqHandler = token;
		token = null;
	} else if ( token ) {
		this.loadToken( token );
	}

	wpcomFactory.call( this, token, function( params, fn ) {
		if ( this.isTokenLoaded() ) {
			// authToken is used in wpcom-xhr-request,
			// which is used for the signup flow in the REST Proxy
			params = assign( {}, params, { authToken: this._token, token: this._token } );
		}

		return reqHandler( params, fn );
	} );

	debug( 'Extending wpcom with undocumented endpoints.' );
}