[DOC Beta] Fixing documentation typo (thanks to @bmac)
[BUGFIX beta] update run.throttle docs with new immediate default
[BUGFIX beta] Only consider requests fired in a single test as pending

In order for the test waiter to work, it needs to keep track of ajax
calls. In the past these calls were tracked by jQuery internally-
eventually we began tracking them via ajaxSend and ajaxComplete. The
simple implementation incremented and decremented a counter.

This solution was too naive, as it meant there was no way to disregard an
xhr that had begun in testA, but was resolving in testB, from the
pending count. testB would then hang on pending XHRs started in testA.

This commit introduces an array, reset on every setupForTesting, that
keeps track of fired xhr requests. When a request completes, the array
is searched for a matching send record. If one is found, the count is
decremented. If one is not found, then the response is ignored and the
count left un-touched.

In this way, only XHRs from testA will hold up waits for testA, and only
XHRs started in testB will hold up waits for testB.
Update CHANGELOG.
[Bugfix beta] [fixes #3444] Prevent an itemController leak

itemControllers/subControllers should be tied to bound to the life cycle of the parent controller.
Ensure that `content` -> `model` alias does not break SemVer.
Update route.js

Update documentation to use getters, [0] is undefined for ember data
Merge pull request #4874 from Aesthetikx/patch-1

Update route.js
cleanup of array_controller

- _subController is not observable so remove get/set’s
- if we have no subControllers, don’t bother keeping the array in sync with arrayContent
- don’t try to access subControllers array beyond it’s length
- idiomatic es6 export default
minor enumerable_utils OCD
subController’s parentController & target properties are now set to the concrete parentController.
Merge pull request #4857 from rjackson/SEMMMMMMVVVVVVVEEEEEEEERRRRRRRR

Ensure that `content` -> `model` alias does not break SemVer.
Merge pull request #4873 from stefanpenner/prevent-item-controller-leak

misc ArrayController cleanup (and bugfix)
Remove global Ember.run reference from itemControllers.
Merge pull request #4879 from rjackson/remove-global-run-from-itemcontroller-tests

Remove global Ember.run reference from itemControllers.
Merge pull request #4555 from mixonic/better-ajax-count

[BUGFIX beta] Only consider requests fired in a single test as pending
Merge pull request #4808 from boazsender/fix-select-typo

Fixing documentation typo
[BUGFIX beta] Spaces in brace expansion throws an error.
[DOC beta] Use non-default example for attributeBindings in TextArea.

Related to pull request #4729
Textarea extension example is using `required` as an example while `required` is now one of the recognised attributes already.
Merge pull request #4888 from rjackson/error-whitespace-in-brace-expansion

[BUGFIX beta] Spaces in brace expansion throws an error.