Sheriff's deputies have arrested the roommate of the woman found shot to death earlier this week.  Investigators say 45-year-old Linda Gabaldon reported finding the body of 53-year-old Rebecca Brau in their Mascot Avenue residence Tuesday afternoon.  The Sacramento Bee says there were inconsistencies in Gabaldon's story, and detectives believe the shooting actually occurred the night before.  Several 911 calls had reported shots fired in the neighborhood Monday night.