Run formatter check only on the latest Elixir version

Author: ImmaculatePine

.travis.yml

@@ -1,6 +1,9 @@
 language: elixir
 sudo: false
-script: MIX_ENV=test mix quality
+script:
+  - if [[ `elixir -v` = *"1.9"* ]]; mix format --check-formatted; fi
+  - credo --strict
+  - mix test
 matrix:
   # Compatible versions are taken from
   # https://hexdocs.pm/elixir/compatibility-and-deprecations.html#compatibility-between-elixir-and-erlang-otp

mix.exs

@@ -10,7 +10,6 @@ defmodule Facebook.Mixfile do
       elixir: "~> 1.0",
       description: description(),
       package: package(),
-      aliases: aliases(),
       deps: deps(),
       source_url: "https://github.com/mweibel/facebook.ex"
     ]
@@ -62,14 +61,4 @@ defmodule Facebook.Mixfile do
       {:ex_doc, ">= 0.19.2", only: :dev}
     ]
   end
-
-  defp aliases do
-    [
-      quality: [
-        "test",
-        "format --check-formatted",
-        "credo --strict"
-      ]
-    ]
-  end
 end