revert pyenv upgrade, see what travis has to offer
revert pyenv upgrade, see what travis has to offer

narekgharibyan/keyvi,hendrikmuhs/keyvi,cliqz-oss/keyvi,hendrik-cliqz/keyvi,cliqz-oss/keyvi,narekgharibyan/keyvi,hendrik-cliqz/keyvi,cliqz/keyvi,cliqz/keyvi,cliqz-oss/keyvi,hendrik-cliqz/keyvi,hendrikmuhs/keyvi,cliqz/keyvi,narekgharibyan/keyvi,narekgharibyan/keyvi,hendrikmuhs/keyvi,cliqz/keyvi,hendrikmuhs/keyvi,cliqz-oss/keyvi,hendrik-cliqz/keyvi