function buildQueryString (options) {
	const query = {};
	if (options.search) query.search = options.search;
	if (options.filters.length) query.filters = JSON.stringify(getFilters(options.filters));
	if (options.columns) query.fields = options.columns.map(i => i.path).join(',');
	if (options.page && options.page.size) query.limit = options.page.size;
	if (options.page && options.page.index > 1) query.skip = (options.page.index - 1) * options.page.size;
	if (options.sort) query.sort = getSortString(options.sort);
	query.expandRelationshipFields = true;
	return '?' + qs.stringify(query);
}
Build a query string from a bunch of options