MAINT upgraded ``.travis.yml``
MAINT upgraded ``.travis.yml``

stringertheory/hmmlearn,yunque/hmmlearn,stringertheory/hmmlearn,hmmlearn/hmmlearn,vchu/hmmlearn,yunque/hmmlearn,aubreyli/hmmlearn,aubreyli/hmmlearn,vchu/hmmlearn,hmmlearn/hmmlearn