fix bug in CWidget::getViewPath()

new attempt fix https://github.com/yiisoft/yii/pull/472

**problem description:**
Application has applied theme.
In theme created folder for widget views, but view file for widget not created.
In this case widget must render file from folder alongside widget, but application throws exception

The problem is that when *getViewPath()* cache paths in *_viewPaths* param *$checkTheme* is ignored.

enviroment for test https://github.com/Ryadnov/yii-issue472