Use archives for specific OTP releases for recent Elixir versions
Use archives for specific OTP releases for recent Elixir versions

https://github.com/hexpm/bob/blob/master/README.md#elixir-builds
While some older combinations may work, we restrict our choices
to Elixir 1.4.0+ and OTP 19.0+.

craigcitro/travis-build,craigcitro/travis-build,andyli/travis-build,andyli/travis-build