Fix typo
[BUGFIX release] Fix #3681.

`Em.arrayComputed` is not presently compatible with lazy CPs. There are a few
issues.

1.  To keep refs up to date, observers stay around as long as the object does.
2.  Those observers can repopulate the cache, but when they do so they fail to
    add dependent keys when the cache was empty.

This commit works around 2. by not removing them in the first place.
Essentially the semantics for `ArrayComputedProperty`s differ from standard
`ComputedProperty`s with regards to laziness.

These observers need to be managed better.  Probably the right thing to do, now
that `recomputeOnce` is no longer necessary, is to:
  1. Fix `Em.computed.sort` to not use `recomputeOnce`;
  2. Fix `Em.arrayComputed` to return a proxy to the cached value;
  3. Teardown array observers when the deps count hits 0.

This will give reduce computed properties semantics much closer to regular
computed properties.  There are two important points to note about this
suggestion:

1.  The cached values would still update synchronously.  This can be improved
    with a lazy array implementation and @wycats's skiplist strategy.
2.  The semantics of an array computed would change such that existing refs
    would only be kept up to date as long as the cache had not been invalidated.
    This is probably fine: the current behaviour is not promised in the
    documentation anywhere and it would be pretty bad practice to keep
    references around rather than `Ember.get`ing them.
ensure all public API's of the container are correctly normalized and validated.

Also ensure internal usages are not validated nor re-normalized.
Updating run loop documentation

Backburner was updated and the documentation for
throttle/debounce/cancel needs to be updated to reflect
new functionality
Upgrade RSVP

- instrumentation hooks for tooling
- still promise/a+ 2.0.2 compliant
- adds support for finally/catch
- adds documuncation
- perf
- cleanup
- several fixes
- no longer brings it's own async, as we just use the run-loop
Account for Ember.Test not being present
update docs
Merge pull request #3830 from stefanpenner/upgrade-rsvp

Upgrade RSVP
Allow `this` (global scope) to be null during module initialization

This is in preparation for ES6ifying things at some point.
Merge pull request #3846 from joliss/this

Allow `this` (global scope) to be null during module initialization
Come back test for `Ember.inspect`

This test was lost on #3883 .
Merge pull request #3895 from tricknotes/test-for-ember-inspect

Come back test for `Ember.inspect`
[BUGFIX Beta] Makes sure you can't use unregistered helpers in templates
Add support for min & max on HTML 5 inputs

This will allow support of the min & max attributes on the `number` and
`range` input types from HTML5.
Merge pull request #3898 from bcardarella/bc-min-max-for-inputs

Add support for min & max on HTML 5 inputs
Merge pull request #3897 from twokul/missing-helper-message

[BUGFIX Beta] Makes sure you can't use unregistered helpers in templates
[NICETHING beta] assert `needs` incompatibility with periods

needs isn't compatible with periods, because ultimately
you're going to need to call get('controllers.foo.bar')
(assuming needs: 'foo.bar'), which doesn't and can't
do what you want.
[BUGFIX beta] New error stack trace

Related [#67](https://github.com/tildeio/router.js/pull/67).
Merge pull request #3876 from twokul/relevant-stack-trace

[BUGFIX Beta] New error stack trace
Merge pull request #3899 from machty/needs-warning

[NICETHING beta] assert `needs` incompatibility with periods