Are artists victims of gentrification? Or the perpetrators of it? Artists move into empty post-industrial spaces and poor neighborhoods, save on rent, create their work, build up studios and communities — and then find they're priced out.   Lisa Adams was evicted twice from L.A.'s downtown Arts District and is worried it's about to happen again. Thirty years ago the area was home to light manufacturing and warehouses. Now it's one of the city's most expensive places to live. "Artists are willing to put up with things that other populations won't," says Lisa, “You are a kind of forerunner to what is to come."