.travis.yml in spree_gateway-3.3.7 vs .travis.yml in spree_gateway-3.4.0

@@ -9,20 +9,22 @@
 env:
   - DB=postgres
   - DB=mysql
 
 gemfile:
-  - gemfiles/spree_3_1.gemfile
   - gemfiles/spree_3_2.gemfile
+  - gemfiles/spree_3_5.gemfile
+  - gemfiles/spree_3_6.gemfile
   - gemfiles/spree_master.gemfile
 
 script:
   - bundle exec rake test_app
   - bundle exec rake spec
 
 rvm:
-  - 2.3.1
-  - 2.2.7
+  - 2.5.1
+  - 2.4.4
+  - 2.3.7
 
 matrix:
     allow_failures:
           - gemfile: gemfiles/spree_master.gemfile