Deprecate Ember.Set (no, not Ember.set)
Replaces META_KEY with `__ember_meta__`

V8 deoptimizes access to the object property:

```javascript
function finishChains() {
  // Access to `obj[META_KEY]` will be deoptimized
  var m = obj[META_KEY], chains = m && m.chains;
  if (chains) {
    // ...
  }
}
```

[Relevant V8 trace](https://gist.github.com/twokul/00b0369dbe86f1ffa011#file-code-asm-L630-L640)
[Hygrogen trace](https://gist.github.com/twokul/dad7e4b671235bd64284#file-hydrogen-cfg-L23837)

Here's the sample that was profiled:

```javascript
function createPeople() {
  var people = [];

  for (var i = 0; i < 500; i++) {
    people.push(
      Ember.Object.create()
    );
  }

  return people;
}
```

Result:

```sh
[benchmark.js] META_KEY createPeople x 306 ops/sec ±0.60% (89 runs sampled)
[benchmark.js] '__ember_meta__' createPeople x 336 ops/sec ±0.60% (87 runs sampled)
```

Related [V8 bug](https://code.google.com/p/v8/issues/detail?id=3167).

Tested against:

+ [V8 3.26](https://github.com/v8/v8/commits/3.26), Chrome 36.0.1985.125.
+ [V8 master](https://github.com/v8/v8/commits/master), Chrome 38.0.2104.0.
Merge pull request #5232 from twokul/meta-key

Replaces META_KEY with `__ember_meta__`
Remove Container.defaultContainer.

This has been deprecated since well before 1.0.0.

In the case that an `Ember.View` is used without a container, we throw a
nice assertion error.
Merge pull request #4459 from mixonic/handlebars-global-path

Revert #3218, replace #4358. Deprecate global access from templates
Merge pull request #5230 from rwjblue/remove-default-container

Remove Container.defaultContainer, but still provide helpful error.
Merge pull request #4124 from mixonic/deprecate-bad-normalize-get

Deprecate edge-case get and normalizeTuple behavior before fixes
Cleanup test failures from #4124.
Merge pull request #5235 from rwjblue/cleanup-test-failures

Cleanup test failures from #4124.
Deprecate Internet Explorer 6 & 7.
Merge pull request #5236 from rwjblue/deprecate-ie-6-7

Deprecate Internet Explorer 6 & 7.
Merge pull request #5229 from trek/deprecate-ember-Set

Deprecate Ember.Set (no, not Ember.set)
jshint
Merge pull request #5243 from mixonic/jshint-navigator

jshint
Polyfill contains for older browsers
Merge pull request #5240 from trek/fix-contains-on-older-firefox

[BUGFIX release]  Fix usage of document.body.contains
refactored compare.js
nodejs apparently does not have Math.sign, also moved TYPE_ORDER to be local to compare.js
Merge pull request #5244 from adamnemecek/compare

Refactored compare.js
removed an unnecessary implementation of indexOf and moved lastIndexOf from native_array.js to array.js