Conflicts:
	framework/CHANGELOG.md

Conflicts:
	framework/CHANGELOG.md

ActiveQuery::one() slight refactoring

This reverts commit a5846fa2, reversing
changes made to 2a6e064a.

Check if property is set

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
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# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.

Merge branch 'defaultValueValidator' of github.com:Alex-Code/yii2 into Alex-Code-defaultValueValidator

Conflicts:
	framework/CHANGELOG.md

Conflicts:
	framework/CHANGELOG.md

* 'mime-types-from-apache' of github.com:yiisoft/yii2:
  changelog
  generated mimeType detection file from apache http mime.types file

Conflicts:
	framework/CHANGELOG.md

MimeTypeController generates a map of file extensions to MIME types

It uses `mime.types` file from apache http located under
http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/conf/mime.types?view=markup

This file has been placed in the public domain for unlimited
redistribution,
so we can use it and ship it with Yii.

see also yiisoft/yii#2851 and yiisoft/yii#2857