disable 2.4.0 builds on unsupported Rubies

Author: JonRowe

.travis.yml

@@ -110,6 +110,19 @@ matrix:
       env: RAILS_VERSION='~> 3.1.12'
     - rvm: 2.3.1
       env: RAILS_VERSION='~> 3.1.12'
+    # MRI 2.4+ is not supported on a few versions
+    - rvm: 2.4.0
+      env: RAILS_VERSION='~> 4.1.0'
+    - rvm: 2.4.0
+      env: RAILS_VERSION=4-1-stable
+    - rvm: 2.4.0
+      env: RAILS_VERSION='~> 4.0.4'
+    - rvm: 2.4.0
+      env: RAILS_VERSION=4-0-stable
+    - rvm: 2.4.0
+      env: RAILS_VERSION='~> 3.2.17'
+    - rvm: 2.4.0
+      env: RAILS_VERSION=3-2-stable
     - rvm: 2.4.0
       env: RAILS_VERSION='~> 3.1.12'
   allow_failures: