WASHINGTON (Reuters) - R&B singer Alicia Keys, country guitar slinger Brad Paisley and pop star Katy Perry are some of the A-list performers who will entertain partygoers at President Barack Obama's inaugural celebration, organizers said on Friday. Smokey Robinson and Stevie Wonder, two prominent elder statesmen of American music, also will perform at one of the three official parties planned for the onset of Obama's second term in office, the inaugural committee said. Other performers include salsa singer Marc Anthony, rappers Far East Movement and Nick Cannon, pop band fun. ...