add absolutePaths option to CFileHelper::findFiles

if absolutePaths is true (by default), function will return absolute paths, otherwise the relative ones
mbstring fallback for CFileHelper::findFiles
code conv fix, charset specifying and docs improvement
Merge remote-tracking branch 'upstream/master' into patch-1
CHANGELOG updated
Merge remote-tracking branch 'upstream/master'
another way to return relative paths: findFilesRecursive main loop instead of findFiles post-processing
CClientScriptTest has been advanced to expose issue #2770
CClientScript::renderScriptBatch() has been fixed to group scripts with different HTML options correctly.
Issue #2770 has been added to CHANGELOG
CClientScript::renderScriptBatch() has been improved to sort html options only if they are specified.
Merge branch 'master' of github.com:yiisoft/yii into 2770-client-script-render-script-batch
use proper table name with schema when creating a multi insert command
detect properly if criteria->select starts with a count() expression in CActiveFinder->count() method
updated CHANGELOG
Merge branch 'master' of git://github.com/yiisoft/yii
Merge branch 'master' into patch-1

Conflicts:
	CHANGELOG
CFileHelperTest.testFindFiles_absolutePaths was added
CFileHelperTest.testFindFiles_relativePaths was added
Merge pull request #2722 from pavel-voronin/patch-1

add absolutePaths option to CFileHelper::findFiles