HomeAway (AWAY), an online marketplace for vacation rentals, has seen profit growth accelerate for two straight quarters as it capitalizes on travelers seeking an alternative to hotel stays. The Austin, Texas-based company reported last week that Q4 profit doubled from a year ago to 14 cents a share, topping analysts' estimates and building on gains of 10% and 27% in Q2 and Q3, respectively. Sales growth has held steady in a range of 20% to 22%