Merge pull request #662 from dgynn/travis_fixes

Fix travis by upgrading bundler

.travis.yml

@@ -1,14 +1,15 @@
-# http://about.travis-ci.org/docs/user/build-configuration/
+# https://docs.travis-ci.com/user/customizing-the-build/
+language: ruby
+cache: bundler
 rvm:
-  - 1.8.7
   - 1.9.3
   - 2.0.0
   - 2.1
   - 2.2
+  - 2.3.1
 notifications:
   recipients:
     - nesquena@gmail.com
     - databyte@gmail.com
-matrix:
-  allow_failures:
-    - rvm: 1.8.7
+before_install:
+  - gem install bundler