* remove ember-cli-favicon
* link to png favicon in public folder
* skip some things in the build depending on the env
* update to ember-cli 3.5.0 for broccoli 2, and ember-fetch because it was incompatible with broccoli 2
* update some things the new sass module wasn't happy about
* turn off more things in dev to make the build faster
* bump to the latest ember-cli and move back to node-sass
* remove sass since we're using node-sass
* include polyfill in test as well
