Export `Store` as default from ./system/store

This allows it to import it simply via `import Store from
"./system/store"` instead of `import {Store} from "./system/store"`.
Upgrade QUnit to v1.13.0

Start using a bower installed version of QUnit.
Use latest stable Ember.js

Note: the jQuery dependency needs to be specified explicitely since
Ember.js v1.3.1 does not support jQuery 2.1
Merge pull request #1697 from pangratz/upgrade_qunit

Upgrade QUnit to v1.13.0
Merge pull request #1688 from pangratz/export_store_as_default

Export `Store` as default from ./system/store
Fix bug where an undefined id would trigger a `findAll`

This has been observed by the eagle eyes of @stefanpenner, reported in
issue #1705.
Merge pull request #1706 from pangratz/youve_gotta_find_them_all

Fix bug where an undefined id would trigger a `findAll`
Object.create does not exist in old IE.
Merge pull request #1708 from rjackson/dont-blow-up-shitty-browsers

Object.create does not exist in old IE.
Remove restriction for jQuery version in bower.json

This was needed since Ember v1.3.1 only works with jQuery <2.1, but the
bower config for this version didn't specify this restriction. Since
this has been fixed by Señor @rjackson (http://git.io/B2xRbQ) the
specific jQuery version is removed again from `bower.json`.
Merge pull request #1710 from pangratz/remove_jquery_dependency_in_bower

Remove restriction for jQuery version in bower.json
Allow testing against multiple versions of Ember & jQuery.

* Adds ability to test against multiple versions of Ember via the
  `emberchannel` query param (defaults to local Bower version).
* Adds ability to test against multiple jQuery versions via the `jquery`
  query param (defaults to local Bower version).
Enable multi-channel testing.

Adds the following tasks:

* `test:local` (alias to previous `test` task)
* `test:release` (tests against current release builds of Ember)
* `test:beta` (tests against current beta builds of Ember)
* `test:canary` (tests against current canary builds of Ember)
* `test:all` (tests against all channels of Ember)

Changes the default Travis test script to `test:all`.
Merge pull request #1709 from rjackson/enable-multi-version-testing

Enable multi-version testing
Fix the links to DS.Model and DS.Transform in the DS Namespace method docs
Merge pull request #1711 from bmac/fix-ds-namespace-links

Fix the links to DS.Model and DS.Transform in the DS Namespace method docs
Add build publishing to builds.emberjs.com.
Merge pull request #1713 from rjackson/publish-builds-again

Add build publishing to builds.emberjs.com.
Ensure builds are generated before publishing.
Destroying the store now:

- unload's all Records
- unload's all RecordArrays
- destroy's all records (so life cycle hooks get called for cleanup)
- destroy's all RecordArrays

Unloading a record now:
- is allowed, unless the record is inflight. (previously it was disallowed for all dirty states)