Add more 1.2.1 changes to changelog
Don't use window.Messenger everywhere so that noConflict will actually
work.
Merge branch 'develop' into develop-pages

Conflicts:
	build/js/messenger.js
	build/js/messenger.min.js
	package.json
	src/coffee/messenger.coffee
Merge branch 'develop-pages' into gh-pages

Conflicts:
	build/js/messenger.js
	build/js/messenger.min.js
	package.json