enable rbf gpu to support psi2n
enable rbf gpu to support psi2n

dhhjx880713/GPy,SheffieldML/GPy,ysekky/GPy,ysekky/GPy,esiivola/GPYgradients,dhhjx880713/GPy,avehtari/GPy,befelix/GPy,esiivola/GPYgradients,dhhjx880713/GPy,mikecroucher/GPy,mikecroucher/GPy,SheffieldML/GPy,SheffieldML/GPy,avehtari/GPy,befelix/GPy,ysekky/GPy,ysekky/GPy,mikecroucher/GPy,SheffieldML/GPy,dhhjx880713/GPy,befelix/GPy,befelix/GPy,esiivola/GPYgradients,esiivola/GPYgradients,mikecroucher/GPy,avehtari/GPy,avehtari/GPy