Allow writing widgets using return instead of echo in the run method to make it consistent with controller
Added echo output in case there's return
Added changelog
Modified phpdoc
Fixed Widget::widget
Merge branch 'master'

Conflicts:
	framework/CHANGELOG.md
Merge pull request #2161 from yiisoft/widget-allow-return-instead-of-echo

Allow writing widgets using return instead of echo in the run method to make it consistent with controller