Enhancing extensibility of CActive* class hierarchy: CActiveFinder and CActiveRecord::model factory methods

Author:    denisarius <denisarius@gmail.com>
Merge branch '1863_enhance_CActive_hierarchy_extensibility' of github.com:denisarius/yii into denisarius-1863_enhance_CActive_hierarchy_extensibility

Conflicts:
	CHANGELOG
Adjusted phpdoc, fixed code style
Merge branch 'origin/master'