.travis.yml in omniauth-oauth2-1.5.0 vs .travis.yml in omniauth-oauth2-1.6.0

@@ -1,15 +1,19 @@
-before_install: gem install bundler
+bundler_args: --without development
+before_install:
+  - gem update --system
+  - gem update bundler
+cache: bundler
 env:
   global:
     - JRUBY_OPTS="$JRUBY_OPTS --debug"
 language: ruby
 rvm:
   - jruby-9000
-  - 2.1.10 # EOL Soon
-  - 2.2.6
-  - 2.3.3
-  - 2.4.0
+  - 2.2.9
+  - 2.3.5
+  - 2.4.4
+  - 2.5.3
   - jruby-head
   - ruby-head
 matrix:
   allow_failures:
     - rvm: jruby-head