Fixed an example of using buildKey in the doc

[READY] jQuery UI accordion rework

[READY] JQuery UI sortable widget

`$this` -> `$self`

Fixed an example of using buildKey in the doc

PHP supports exception stacks since 5.3 so we should use it.
Also Errorhandler is now able to display the stack: #297

make sure all information is displayed
Fixes comment by @creocoder issue #408
https://github.com/yiisoft/yii2/pull/408#issuecomment-18454179

git ignore composer.lock

[READY] jQuery UI autocomplete widget rework

[READY] jQuery UI DatePicker widget