* master: (33 commits)
  Skipped ApcCacheTest expire
  MS Windows EOLs → UNIX EOLs.
  Build command path fix.
  refactored RBAC.
  Added usage example of Theme.
  Added default class for theme.
  Fixes issue #172: Implemented new usage of widgets.
  code style fix of YiiRequirementChecker.php Renamed yiirequirements.php to requirements.php
  "YiiRequirementChecker" console view has been reworked to display requirements by blocks and in brief for the successful ones.
  Changed framework in dir structure to yii
  requirements.php typo fix.
  "requirements.php" has been added to "bootstrap" application.
  Doc comments and error messages for "YiiRequirementChecker" have been adjusted.
  Doc comments for "YiiRequirementChecker" have been updated.
  PHP version fallback for "YiiRequirementChecker" has been added.
  "YiiRequirementChecker::check()" has been updated allowing to accept filename for the requirements. Yii core requirements file has been composed.
  Check helper methods have been added to "YiiRequirementChecker".
  Web view for "YiiRequirementChecker" has been created.
  "YiiRequirementChecker::render()" has been implemented, console view has been created.
  added newline to end of header and body blocks in View
  ...

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.

Yii core requirements file has been composed.

issue #237

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.

RBAC: DbManager code style

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