Pin Faraday to 0.17.0 for Ruby 1.9
Pin Faraday to 0.17.0 for Ruby 1.9

0.17.1 is incompatible with 1.9, so, until
https://github.com/lostisland/faraday/pull/1086 or similar is released,
we need to stay on 0.17 for 1.9.

travis-ci/travis.rb,travis-ci/travis.rb,travis-ci/travis.rb