[travis] added retries for installing conda, as it seemed to fail on 404 errors
[travis] added retries for installing conda, as it seemed to fail on 404 errors

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