added unit test for param tie at the kernel level
added unit test for param tie at the kernel level

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