Fix #87: security helper converted into component and improved

Chinese Translation for this week

* upstream/master:
  Reverted #4098.
  fix duplicated white space and typo [skip ci]
  typo fix
  Fixes #4098: `yii\db\Query::addSelect()` should include `*` when it is called the first time

fix duplicated white space and typo [skip ci]

* upstream/master:
  typo fixes [skip ci]

Upgrade Bootstrap from 3.1 to 3.2

Fix json format in gii/generators/extension/default

* upstream/master:
  resolved naming conflict in apidoc

* upstream/master:
  gridview and listview use widget ID in base tag
  typo fix [skip ci]
  Update CHANGELOG.md
  made elasticsearch error messages more readable
  Spanish structure-views [skip ci]
  Fix filename
  Update README.md
  https://github.com/yiisoft/yii2/pull/4091#discussion_r14296860
  Fix possibility of non-removed symlinked directory.
  Fixed typo. [skip ci]
  changed default for rotateByCopy of FileTarget