.travis.yml in review-2.1.0 vs .travis.yml in review-2.2.0

@@ -1,25 +1,18 @@
 language: ruby
 sudo: false
 
 before_install:
+  - gem update --system
   - gem update bundler
 
 rvm:
-  - 2.0.0
-  - 2.1.*
-  - 2.2.*
-  - 2.3.1
+  - 2.0
+  - 2.1
+  - 2.2
+  - 2.3.3
+  - 2.4.0
 ##  - ruby-head
 
-addons:
-  apt_packages:
-    - libgmp3-dev
-
 branches:
   only:
     - master
-
-script:
-  - bundle exec rake test
-  - bundle exec rubocop
-