message: Add boost1.68 to Travis CI configuration
diff: @@ -10,11 +10,13 @@ os:
  addons:
  apt:
  sources:
  + - mhier/libboost-latest
  - ubuntu-toolchain-r-test
  - llvm-toolchain-precise-3.8
  packages:
  - g++-7
  - - libboost-all-dev
  + - libboost1.68
  + - libboost1.68-dev
  - libssl-dev
  - clang-3.8
  - build-essential
  