.travis.yml: speed up builds
.travis.yml: speed up builds

iksaif/biggraphite,iksaif/biggraphite,iksaif/biggraphite,criteo/biggraphite,iksaif/biggraphite,criteo/biggraphite,Thib17/biggraphite,criteo/biggraphite,Thib17/biggraphite,Thib17/biggraphite,Thib17/biggraphite,criteo/biggraphite