Allow Ruby 2.4.0 to fail for now

lord · lord · commit 7ae2192b75dd · 2017-02-23T21:50:02.000-06:00
diff --git a/.travis.yml b/.travis.yml
@@ -9,3 +9,7 @@ rvm:
 
 cache: bundler
 script: bundle exec middleman build
+
+matrix:
+  allow_failures:
+  - rvm: 2.4.0
