Remove support for AA 0.6.6 and Rails 3.2

These dependencies are quite old and are causing build failures.

Author: zorab47

.travis.yml

@@ -4,20 +4,15 @@ rvm:
   - 2.2
   - 2.3
   - 2.4
+  - 2.5
 
 env:
-  - RAILS_VERSION=3.2
   - RAILS_VERSION=4.2
   - RAILS_VERSION=5.0
   - RAILS_VERSION=5.1
 
 matrix:
   exclude:
-    - rvm: 2.2
-      env: RAILS_VERSION=3.2
-    - rvm: 2.4
-      env: RAILS_VERSION=3.2
-
     - rvm: 2.2
       env: RAILS_VERSION=5.0
     - rvm: 2.2