Merge pull request #90 from academe/issue89

Clear up some token billing ambiguities.

This PR has a lot more changes than I would normally like, but contains more tests in areas that have been refactored, so should be stable. I am going to try it in production for a week before making a minor release.

This version drops support for PHP5.3, which has allowed traits to be used to reduce some duplicate methods (the notification handler does not inherit from the Response class, but shares many of its methods).

.travis.yml

@@ -4,6 +4,7 @@ php:
   - 5.4
   - 5.5
   - 5.6
+  - 7.0
   - 7.1
   - hhvm