Bump travis versions and remove precise

Author: kpaulisse

.travis.yml

@@ -3,15 +3,14 @@
 language: ruby
 install: true
 script: "script/cibuild"
-dist: precise
 
 matrix:
   include:
     # Build with latest ruby
-    - rvm: 2.4.1
+    - rvm: 2.4
       env: RUBOCOP_TEST="true" RSPEC_TEST="true"
     # Build with older ruby versions
-    - rvm: 2.3.4
+    - rvm: 2.3
       env: RUBOCOP_TEST="false" RSPEC_TEST="true"
     - rvm: 2.2
       env: RUBOCOP_TEST="false" RSPEC_TEST="true"