Minor fixes.
normalize header names.
Added DataProvider and IDataProvider.
Merge branch 'master' of github.com:yiisoft/yii2
Added support for using callables as "ActiveQuery::indexBy".
Virtual properties documentation has been added to "web\Session"
Refactored Query and ActiveQuery.
Finished ActiveDataProvider.
Merge branch 'master' of github.com:yiisoft/yii2
renamed Command::queryRow() to queryOne().
Added class doc.
Refactored ActiveDataProvider.
Allow customizing DB connection for ActiveDataProvider.
Added unit test for ActiveDataProvider.
Finished unit test of ActiveDataProvider.
Fixed test break.