Cover the bottom of the crock pot with the sliced onions.  Mix all spices in a small bowl and then rub the spice mixture all over the whole chicken.  Place the spiced chicken on top of the onions in the crock pot, cover and cook on low for 5-6 hours (depending on your crock pot).  No need for any liquid, the chicken will cook in it's own juices.  Make sure you spoon the onions and a little bit of the juices over the chicken when you serve it.  I served my chicken with our favorite brussel sprouts, steamed for 5 minutes and then sauteed with a little olive oil, dried dill, garlic powder, and pepper.