chore: use grunt-conventional-changelog

Merge the changelog task into Brian's grunt-conventional-changelog plugin:
https://github.com/btford/grunt-conventional-changelog/pull/13
chore: add auto release task
docs(requirejs): update example to work on IE9

As this file is loaded into the browser, it must not contain any ES5-only methods/functionality. It's still very common to need tests for IE 8 & 7 and this code is currently causing an error in those.