One of Sacramento's favorite local bands is local no more. Agent Ribbons will no longer be based in Sacramento. After a farewell show Thursday night at Old Ironsides, singer/songwriter/guitarist Natalie Gordon is going to be calling Austin, Texas home. At least for a little while. "I'm going down there with the intention of moving back to Sacramento at some point," Gordon said on the phone Wednesday before the band played a gig in San Francisco. "But I want to try somewhere new. My life's just really open right now." The band, which began as a duo consisting of Gordon and drummer/singer Lauren Hess, became a trio in the last couple of years with the addition of violinist Naomi Cherie,