corrected autodiff_test to test for correctly returned output from jacobian; NEEDS REVIEW as output from the nested AD calculations is ONLY correct if a dummy var variable is initialized
corrected autodiff_test to test for correctly returned output from jacobian; NEEDS REVIEW as output from the nested AD calculations is ONLY correct if a dummy var variable is initialized

stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math