language: ruby
rvm:
  - 1.8.7
  - 1.9.2
  - 1.9.3
  - 2.0
  - 2.1
  - 2.2

language: ruby
rvm:
  - 2.0
  - 2.1
  - 2.2

Update Travis CI config, remove Ruby 1.x.
Update Travis CI config, remove Ruby 1.x.

1.9.3 fails because json_pure requires Ruby ~> 2.0. Other old versions
fail for similar reasons.
