Add v4.0.0-beta.8 to CHANGELOG
Add v4.0.0-beta.8 to CHANGELOG

(cherry picked from commit f7d7b24222fe325fa34f102ae16843dc5db8ee1a)

emberjs/ember.js,mixonic/ember.js,sly7-7/ember.js,emberjs/ember.js,emberjs/ember.js,mixonic/ember.js,tildeio/ember.js,sly7-7/ember.js,sly7-7/ember.js,mixonic/ember.js,tildeio/ember.js,tildeio/ember.js