bump ruby versions for travis, add rails-5.2

Author: lostapathy

.travis.yml

@@ -5,14 +5,16 @@ rvm:
   - 1.9.3 # when removed, get rid of the before_script hack and also the one in application_generator.rb
   - 2.0.0
   - 2.1.10
-  - 2.2.7
-  - 2.3.4
-  - 2.4.1
+  - 2.2.10
+  - 2.3.7
+  - 2.4.4
+  - 2.5.1
   - ruby-head
 env:
   - RAILS_VERSION="~> 4.2.0"
   - RAILS_VERSION="~> 5.0.0"
   - RAILS_VERSION="~> 5.1.0"
+  - RAILS_VERSION="~> 5.2.0"
 matrix:
   exclude: # Rails 5 is incompatible with Ruby < 2.2.2
     - rvm: 1.9.3
@@ -27,6 +29,12 @@ matrix:
       env: RAILS_VERSION="~> 5.1.0"
     - rvm: 2.1.10
       env: RAILS_VERSION="~> 5.1.0"
+    - rvm: 1.9.3
+      env: RAILS_VERSION="~> 5.2.0"
+    - rvm: 2.0.0
+      env: RAILS_VERSION="~> 5.2.0"
+    - rvm: 2.1.10
+      env: RAILS_VERSION="~> 5.2.0"
   allow_failures:
     - rvm: ruby-head
   fast_finish: true