remove caching from travis (seems to be useless)
remove caching from travis (seems to be useless)


Former-commit-id: 6fd234fe7f7c4395a906250cd4bb0143abaef1f8
kermitt2/grobid,kermitt2/grobid,kermitt2/grobid,kermitt2/grobid,kermitt2/grobid,kermitt2/grobid