Wayfair, the online home furnishings company, is on track to hire 1,000 workers for its operations opening this summer in Maine, a company executive said Thursday. Liz Graham, the company’s vice president for sales and service, said Wayfair is on track to open its sales and customer service operation at Brunswick Landing in Brunswick next month and another operation in Bangor in July. The company sells a broad range of products, from furniture to flooring, lighting, plumbing and appliances.