.travis.yml: see if this is simpler to maintain.
.travis.yml: see if this is simpler to maintain.

bpollack/factor,bpollack/factor,tgunr/factor,bpollack/factor,bpollack/factor,mrjbq7/factor,factor/factor,factor/factor,mrjbq7/factor,mrjbq7/factor,tgunr/factor,mrjbq7/factor,factor/factor,tgunr/factor,factor/factor,mrjbq7/factor,factor/factor,mrjbq7/factor,bpollack/factor,bpollack/factor,bpollack/factor,tgunr/factor,tgunr/factor,factor/factor,tgunr/factor