closed #4529: Stroke size and shadow offset don't consider ContentScaleFactor
closed #4530: Using 'Outside stroke' instead of 'Inside Stroke' for Label generated by 'Font name'. And fix stroke could not work on iOS7.
LabelTest , changed stroke color  to blue.
Adds another test for stroke.
Merge branch 'develop-label-stroke' of https://github.com/dumganhar/cocos2d-x into develop_label_fixs
label: Refactor implementation of shadow.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into develop_label_fixs

Conflicts:
	cocos/2d/CCLabel.cpp
remove unused code and fixed warning.
Merge pull request #5980 from Dhilan007/develop_label2

Refactor implementation of label's shadow and fixed stroke was not 'outside stroke' for Label generated by 'Font name'