.travis.yml in terraforming-0.6.2 vs .travis.yml in terraforming-0.7.0

@@ -1,8 +1,9 @@
 language: ruby
 rvm:
-- 2.2.3
-- 2.1.7
+- 2.3.0
+- 2.2.4
+- 2.1.8
 - 2.0
 env:
 - secure: n0mxwnyjuXI4mJO4mp++2TnsPJ+XgCF/J1U2L5piE5j3xMhSU+5V0JrA1uFlS0Pemb44M7BjgmF9S4G35BwyAQpctpCYhqy9tFa6+Y6nxEv5hCv2cZz7BSAZM6eb+zq20409hxTHRaQOr1DBeE4R5S2PrmOXRqvYfTRv3LNSLFk=
 notifications:
   slack: