.travis.yml in pubnub-4.0.17 vs .travis.yml in pubnub-4.0.18

@@ -11,9 +11,10 @@
 
 script: bundle exec rspec
 
 matrix:
   include:
+    - rvm: 2.4.0
     - rvm: 2.3.1
     - rvm: 2.2.5
     - rvm: 2.1.9
 #    - rvm: jruby-9.1.5.0
 #      env: JRUBY_OPTS="--server -J-Xms1500m -J-Xmx1500m -J-XX:+UseConcMarkSweepGC -J-XX:-UseGCOverheadLimit -J-XX:+CMSClassUnloadingEnabled"