Update exclusion matrix for new rubies

Author: pixeltrix

.travis.yml

@@ -31,20 +31,24 @@ matrix:
       gemfile: Gemfile
     - rvm: 2.0.0
       gemfile: Gemfile
-    - rvm: 2.1.8
+    - rvm: 2.1.9
       gemfile: Gemfile
     - rvm: 1.9.3
       gemfile: gemfiles/Gemfile-5-0-stable
     - rvm: 2.0.0
       gemfile: gemfiles/Gemfile-5-0-stable
-    - rvm: 2.1.8
+    - rvm: 2.1.9
       gemfile: gemfiles/Gemfile-5-0-stable
     - rvm: 1.9.3
       gemfile: gemfiles/Gemfile-edge
     - rvm: 2.0.0
       gemfile: gemfiles/Gemfile-edge
-    - rvm: 2.1.8
+    - rvm: 2.1.9
       gemfile: gemfiles/Gemfile-edge
+    - rvm: 2.4.0
+      gemfile: gemfiles/Gemfile-4-0-stable
+    - rvm: 2.4.0
+      gemfile: gemfiles/Gemfile-4-1-stable
 
 notifications:
   email: false