[WIP DO NOT REVIEW] Remove EmberJSBuild, Update Babel, Remove Cycles

[chadhietala]

Unfortunately for us to move forward with many efforts we have to shave some yaks. Below are the known issues this PR is attempting to fix:

• Remove ember-metal and ember-debug cycle
• Have the ability to remove the internal loader
• Allow Ember to ship loose modules so it easier to make ember pay-as-you-go in terms of file size(prerequisite for RFC#176)
• Introduce Babel 6
• Introduce better debug and assertion stripping (Requires Babel 6).
• Tee up the ability to remove all deprecated code <= a version supplied by the app a build. Also known as Svelte. (Requires Babel 6).

[homu]

☔ The latest upstream changes (presumably #15005) made this pull request unmergeable. Please resolve the merge conflicts.

[chadhietala]

Ya not rebasing this. Will cherry pick the commits over.