infra: make travis use make (no pun intended)
infra: make travis use make (no pun intended)

Also use container-based builds and 4 python versions.

Signed-off-by: Pavel Kulyov <661f9993ccc93424ad20871d2ea98bc2860e5968@gmail.com>

pankshok/xoinvader,pkulev/xoinvader