[BUGFIX beta] Remove false attribute from Ember.View

In IE8 (or older), `jQuery.fn.prop` always update DOM against our
expectation.(This is a jQuery bug but it couldn't fix)
ref: http://bugs.jquery.com/ticket/13558

So the following test is failed due to `view.$().attr('foo')` returns `"false"`.:
* https://github.com/emberjs/ember.js/blob/a449d445/packages/ember-views/tests/views/view/attribute_bindings_test.js#L126

To avoid this issue, `removeAttr` should be called when `null`, `undefined` or `false` is given as value.

But this way contains incompatible changes:

Before:
``` javascript
view.set('checked', false);
view.$().prop('checked'); //=> false
```

After:
``` javascript
view.set('checked', false);
view.$().prop('checked'); //=> undefined
```
[Bugfix beta] improve action without actions hash deprecation warning
Remove a .swp file
Update ember-dev
Use expectAssertion instead of manual assert stubbing
Introduce expectDeprecation. Remove TESTING_DEPRECATION.
[BUGFIX beta] Silently fail when disconnecting from an inactive view
Add documentation for Ember.EnumerableUtils.
Merge pull request #4129 from LevelbossMike/master

Add documentation for Ember.EnumerableUtils.
Merge pull request #4125 from mixonic/disconnect-outlet-without-parent

[BUGFIX beta] Silently fail when disconnecting from an inactive view
Merge pull request #4123 from mixonic/expect

Use new expectDeprecation helper in tests, remove TESTING_DEPRECATION
Merge pull request #4114 from stefanpenner/improve-deprecation-message

[Bugfix beta] improve action without actions hash deprecation warning
Route#disconnectOutlet accepts a string
Merge pull request #4091 from bradfol/disconnectOutlet

Route#disconnectOutlet accepts a string
remove unneeded get
we now have multi-line asserts, lets use them!
Merge pull request #4066 from tricknotes/fix-to-remove-attrs

[BUGFIX beta] Remove false attribute from Ember.View for IE8
Remove `Ember.handleErrors`
Merge pull request #3940 from sandstrom/handle-errors

Remove `Ember.handleErrors`