LONDON (Reuters) – Singer-songwriter Ebony Day has been named MTV’s act to watch in 2013 before even signing a record deal, underlining how up-and-coming artists are increasingly using the internet and social networking sites to build a significant fan base. Inspired by the viral success of Canadian teen sensation Justin Bieber, the 19-year-old Briton posted a series of online videos performing cover versions, and quickly amassed a sizeable following – 18 million views on her YouTube channel and 156,000 subscribers to date. …