optimize travis-ci build a bit more
optimize travis-ci build a bit more

frett/cas,tduehr/cas,robertoschwald/cas,robertoschwald/cas,robertoschwald/cas,frett/cas,GIP-RECIA/cas,rrenomeron/cas,rrenomeron/cas,rrenomeron/cas,robertoschwald/cas,GIP-RECIA/cas,tduehr/cas,GIP-RECIA/cas,tduehr/cas,tduehr/cas,GIP-RECIA/cas,frett/cas,frett/cas,rrenomeron/cas,GIP-RECIA/cas,rrenomeron/cas