This is not allowed by phpunit as a test may not fail anymore

 Method "yii\console\controllers\AssetController::buildTarget()" has been fixed to compose input file name correctly.

- better throw http exception on not satisfiable range request
- constitent header names
- fixed range end when range request is to the end
- added unit test

related to #275, fixes #148

https://github.com/yiisoft/yii2/commit/e2513de6c6207fa37894a944e10b8cd420ac6804#commitcomment-3192244

"YiiRequirementChecker::check()" has been updated to be able to collect different requirements set in the chained call.

as discussed in #203
https://github.com/yiisoft/yii2/issues/203#issuecomment-17759631

Methods "YiiRequirementChecker::getResults()" and "YiiRequirementChecker::render()" have been added.

change is to avoid random test failure on race condition.
fixes #203 #231

- rename requireApp() to mockApplication()
- always destroy app on tearDown()
  - eliminates need for constant YII_DESTROY_APP_ON_TEARDOWN
  - mockApplication() becomes a lot easier. Destroying app on each tearDown
    means creating it on every call is fine. No more checking if it already
    exists and if it has been created from the same config.
- \yii::$app should have been \Yii::$app