advanced file excluding/including ported from git
improved comments, method visiblity and exceptions
refactored flag names
more unit tests for helpers/FileHelper::findFiles using new wildcard exceptions matching
remove _FLAG from PATTERN_FLAG constants
updated helpers/BaseFileHelper::findFiles description and comments in messages/config.php
fixed code style for assignments inside if conditions
Merge branch '2048-improve-messages-config-exceptions' of github.com:nineinchnick/yii2 into nineinchnick-2048-improve-messages-config-exceptions

Conflicts:
	framework/messages/config.php