Reports new notification data if available

New notification data is available _if_ we
have a note with a timestamp newer than we
did the last time we called this function.
function ready() {
	const notes = getAllNotes( store.getState() );

	const timestamps = notes
		.map( property( 'timestamp' ) )
		.map( timestamp => Date.parse( timestamp ) / 1000 );

	let newNoteCount = timestamps.filter( time => time > this.lastSeenTime ).length;

	if ( ! this.firstRender && this.lastSeenTime === 0 ) {
		newNoteCount = 0;
	}

	const latestType = get( notes.slice( -1 )[ 0 ], 'type', null );
	store.dispatch( { type: 'APP_RENDER_NOTES', newNoteCount, latestType } );

	this.hasNewNoteData = false;
	this.firstRender = false;
}