Container creates a Registry if none is supplied.

In order to avoid breaking existing usages of Container in the wild, an
isolated registry will be created if none is supplied to the
constructor. This behavior is deprecated.

Note: This commit includes a temporary workaround for the lack of 
support for circular module dependencies in v0.4.0 of the ES6 
transpiler.
Perhaps
```js
this._registry = registry || (function() {
  Ember.deprecate("A container should only be created for an already instantiated registry. For backward compatibility, an isolated registry will be instantiated just for this container.");
  // TODO - See note above about transpiler import workaround.
  if (!Registry) { Registry = requireModule('container/registry')['default']; }
  return new Registry();
}());
```
Though line 32 is `options = options || {};`, which is a widely-used pattern.