Fix YiiRequirementChecker.php typo

also changed PHP Intl support to optional.

* 'master' of github.com:yiisoft/yii2: (31 commits)
  Finished bootstrap Widget and Modal.
  PHP Intl extension has been added to default Yii requirements.
  moved optional packages to "suggest", updated platform requirements
  "vendor-dir": "vendor" is default, removed
  Fixes issue #320: Module::createController() will fail with a route with trailing slash.
  Fixed test break about AssetController.
  requirements css.php twitter bootstrap update to 2.3.2
  Twitter bootstrap updated to 2.3.2
  Modified the IAssetConvert interface.
  hashing the key for registerCss and registerJs.
  Update AccessRule.php
  refactored code after feedback
  Fixed framework path.
  Added support for View::POS_READY.
  new proposed structure
  remove from master (update track)
  minor fixes
  updated the README file of the bootstrap app.
  Inflector class
  readjusting files for the framework package.
  ...

fixed range requests, tests improved

Bootstrap proposed architecture

requirements css.php twitter bootstrap update to 2.3.2

AccessRule match controller error.

Twitter bootstrap updated to 2.3.2