LONDON (Reuters) – Royal Bank of Scotlands new boss admitted the state-backed bank had under-invested in its systems for decades and apologized for an unacceptable technology crash that affected more than 1 million customers on Monday. For decades, RBS failed to invest properly in its systems, said Ross McEwan, who became chief executive in October. I will be outlining plans in the New Year for making RBS the bank that our customers and the UK need it to be. This will include an outline of where we intend to invest for the future. …