.travis.yml in rib-1.2.91 vs .travis.yml in rib-1.3.0

@@ -1,15 +1,15 @@
 sudo: false
 language: ruby
 rvm:
   - 2.1
   - 2.2
-  - 2.3.0
+  - 2.3.1
   - rbx
   - jruby-9
 
 before_install:
   - rvm get head
   - rvm reload
   - rvm use --install $TRAVIS_RUBY_VERSION --binary --latest
-install: 'bundle install --retry=3'
+install: 'gem install bundler; bundle install --retry=3'
 script: 'ruby -r bundler/setup -S rake test'