add changelog and check

.travis.yml

@@ -11,6 +11,7 @@ script:
   - mkdir upload
   - cd dist; zip -r ../upload/dist.zip *; cd -
   - .travis/echo_sha.sh > upload/data.json
+  - rvm use 2.3.1 && gem install danger --version '~> 4.0' && danger
 
 deploy:
   provider: s3

CHANGELOG.md

@@ -0,0 +1,8 @@
+# Change Log
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/).
+
+(Note for Alex: fill in what kind of versioning we want to use)
+
+## [Unreleased]

Dangerfile

@@ -0,0 +1,6 @@
+# Add a CHANGELOG entry for app changes
+has_app_changes = !(git.modified_files.grep(/js/).empty? || git.modified_files.grep(/scss/).empty?)
+if !git.modified_files.include?("CHANGELOG.md") && has_app_changes
+  fail("Please include a CHANGELOG entry.")
+  message "See http://keepachangelog.com/en/0.3.0/ for details on good changelog guidelines"
+end