(Reuters) - Short-seller Citron Research on Wednesday backed Facebook Inc , saying the stock could hit $160 (126.13 pounds) in 2019 as the company's revenue and user base have seen little impact from the reported data scandals and privacy issues this year.Shares of the social network rose as much as 4.4 percent to $129.57 after Citron's report. They are down 28 percent this year."We believe investors will be rewarded by the shift of user behaviour to Instagram shopping and the personalisation of..