[DOC beta] minor doc fix
[DOC beta] Make `Ember.computed.collect` visible in docs
[BUGFIX beta] Do not use ENV if EmberENV exists.

This allows the use of `ENV` in your application without having Ember
hijack it for its uses.

To avoid using `window.ENV`, but still provide customization to Ember's
boot process you could use something like the following:

```javascript
ENV = 'DO NOT USE ME!!!!';

EmberENV = {DISABLE_RANGE_API: true};
```

Conflicts:
	packages/metamorph/lib/main.js