Fixes #2701
Update CHANGELOG.md

updated changelog about isEmpty bug.
Improved check for active child items

Updated to avoid full tree traversal.
Also noticed ```activateItems``` didn't do anything so that's been fixed.
Update CHANGELOG.md
Update CHANGELOG.md
Merge branch 'fix_is_empty_file_validator' of github.com:ZhandosKz/yii2 into ZhandosKz-fix_is_empty_file_validator

Conflicts:
	framework/CHANGELOG.md
fixed the build command after controller namespace changes
updated `@property` annotations
Update i18n.md
Merge pull request #2704 from ShNURoK42/patch-3

Update i18n.md
tabs vs spaces
Merge pull request #2705 from RusAlex/140311_tabs_vs_spaces

tabs vs spaces
Fixes #2687: table alias may not be respected when specified in relation query.
fixed refences
fixed another reference
more reference fixes
Added asElapsedTime function
Typo in asElapsedTime description
Call Yii::t everytime instead of passing a template variable
Typo