- 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

class name is alwarys HttpException, better display the name of the http
error.

Merge PR #275 branch 'partial-response-enh' of https://github.com/Ragazzo/yii2 into Ragazzo-partial-response-enh

* 'partial-response-enh' of https://github.com/Ragazzo/yii2:
  string helper fixed, mime-type reverted
  code style fix
  partial response added, new code-style applied

Fixed issue with getting Object component

Fixes #226: atomic operations and transaction support in AR.

RBAC: Item and Assignment optimized save approach

Renamed yiirequirements.php to requirements.php

"YiiRequirementChecker" console view has been reworked to display requirements by blocks and in brief for the successful ones.