added cholesy backprop test
added cholesy backprop test

dhhjx880713/GPy,beckdaniel/GPy,befelix/GPy,SheffieldML/GPy,buntyke/GPy,Dapid/GPy,ptonner/GPy,AlexGrig/GPy,ysekky/GPy,ptonner/GPy,SheffieldML/GPy,SheffieldML/GPy,dhhjx880713/GPy,maaskola/GPy,Dapid/GPy,Dapid/GPy,SheffieldML/GPy,PredictiveScienceLab/GPy,ysekky/GPy,buntyke/GPy,beckdaniel/GPy,AlexGrig/GPy,PredictiveScienceLab/GPy,esiivola/GPYgradients,esiivola/GPYgradients,mikecroucher/GPy,PredictiveScienceLab/GPy,ptonner/GPy,PredictiveScienceLab/GPy,maaskola/GPy,ptonner/GPy,AlexGrig/GPy,jameshensman/GPy,buntyke/GPy,maaskola/GPy,dhhjx880713/GPy,avehtari/GPy,AlexGrig/GPy,mikecroucher/GPy,jameshensman/GPy,beckdaniel/GPy,Dapid/GPy,maaskola/GPy,esiivola/GPYgradients,befelix/GPy,avehtari/GPy,befelix/GPy,dhhjx880713/GPy,beckdaniel/GPy,avehtari/GPy,ysekky/GPy,mikecroucher/GPy,mikecroucher/GPy,jameshensman/GPy,befelix/GPy,esiivola/GPYgradients,avehtari/GPy,buntyke/GPy,jameshensman/GPy,ysekky/GPy