install bundler without ri and rdoc

Author: jazzido

Diff for: .travis.yml

@@ -2,7 +2,7 @@ sudo: false
 language: ruby
 before_install:
   - gem update --system
-  - gem install bundler
+  - gem install bundler --no-ri --no-rdoc
 jdk:
   - oraclejdk9
   - openjdk10