Improve travis ci build perfomance
Improve travis ci build perfomance


Former-commit-id: 136ed245a973aadcfb5d2e5b7cb50203bfd67175
exonum/exonum,exonum/exonum,alekseysidorov/exonum,alekseysidorov/exonum,exonum/exonum,alekseysidorov/exonum,alekseysidorov/exonum,exonum/exonum