Allow more configurability in production builds.

```
DISABLE_ES3=true DISABLE_JSHINT=true DISABLE_MIN=true ember serve --environment=production
```

Takes initial production build time from 70s to 21s, and rebuilds from
6s to 2s.
[BUGFIX beta] Make mandatory setter more helpful.
[BUGFIX beta] Bump HTMLBars to fix IE9 issues

Conflicts:
	bower.json
[BUGFIX beta] Assert state of DOM for property changes instead of using jQuery
[DOC beta] Fix isEmpty description
Refactor Ember.platform.

Split various polyfils into separate files.  This will ultimately be
pulled into 1.8 beta series.

Conflicts:
	packages/ember-metal/lib/main.js
[BUGFIX beta] Only tests mandatory-setter in ES5 browers.
[BUGFIX beta] Remove trailing commas for old IE.

Conflicts:
	packages/ember-metal/tests/mixin/concatenatedProperties_test.js
	packages/ember-routing/lib/location/history_location.js
Ensure consistent use of Ember.create.

Conflicts:
	packages/ember-metal-views/tests/test_helpers.js
	packages/ember-metal/lib/mixin.js
	packages/ember-metal/lib/streams/stream.js
	packages/ember-routing/lib/system/router.js
	packages/ember-views/lib/views/view.js
[BUGFIX release] Enable testing of production builds.

Update the build process to emit `ember-testing.js` which contains the
`ember-debug` and `ember-testing` packages.  This file can be include
when running tests against production builds of Ember (`ember.prod.js`).
[BUGFIX beta] Remove use strict mode for Object.create usage.

Work around the bug identified in https://bugs.webkit.org/show_bug.cgi?id=138038,
by removing `'use strict';` from modules where `Object.create` is called
directly (in the case of `Ember.CoreObject` this occurs after inlining).

Conflicts:
	package.json
[BUGFIX beta] Fix isEmpty for map

Conflicts:
	packages/ember-metal/lib/is_empty.js