update backburner

included updated documentation for the run loop as well
DRY up container tests.
Fixes #4201
[BUGFIX beta] Fix component registration tests under IE8.

In IE8 whitespace between `<div>` elements is not respected, causing
these tests to fail.
[FEATURE query-params-new] Fix failures in IE8.

IE8 does not allow `String.substr` to accept negative values. Replacing
with `slice` works well.

@raytiley / @rjackson
[FEATURE query-params-new] Fix issue with tests in IE8.

`DOMElem.classList` does not exist in IE8.

@raytiley / @rjackson
Merge pull request #4243 from rjackson/fix_component_tests

[BUGFIX beta] Fix component registration tests under IE8.
Merge pull request #4242 from rjackson/update-ember-dev

Resolve issue with ember-dev using Object.create in teardown hooks.
Merge pull request #4244 from rjackson/fix-qpn-in-ie8

[FEATURE query-params-new] Fix failures in IE8.
[FEATURE ember-routing-bound-action-name]

The `{{action}}` helper will now use a non-quoted parameter and perform
a bound property lookup against the action's target at the time the
event is triggered.

If a non-quoted param is used, but the property lookup returns
`undefined` a helpful assertion is made, and the specified parameter is
used as a plain string action name (thus preventing this from breaking
anyones applications).

Also, cleans up a few unrelated non-quoted uses of `{{action}}` in the
test suite.
Merge pull request #3936 from rjackson/bound_action_name_lookups

[FEATURE ember-routing-bound-action-name]
[DOC] Minor doc fix
Merge pull request #4247 from twokul/triggerAction-doc

[DOC] Minor doc fix
[FEATURE ember-metal-computed-empty-array]

Make `Em.computed.empty` respect arrays automatically, without users having to
know to use `array.[]`.
[FEATURE ember-handlebars-log-primitives]
Merge pull request #4252 from mmun/log-primitives

[FEATURE ember-handlebars-log-primitives]
[BUGFIX beta] Make Ember.RenderBuffer#addClass work as expected.
[DOC beta] Fix in controllerName comment
Merge pull request #4254 from MajorBreakfast/patch-3

Fix in controllerName comment
[FEATURE ember-eager-url-update] non a-tags work

Eager url updating was breaking for non a tags 
since their hrefs weren't being generated.

Thanks @jonnii for pointing this out