issue #4337:label support create by font name,compatible with old labelTTF
1.fixed color and opacity has not yet gone into effect.
2.fixed display is not consistent with old LabelTTF when content scale factor of Director not equal to 1.
update test case.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into develop
Add conditions to evaluate for setter of font size and font name.
fixed incorrect initial value of label type.
Merge pull request #5679 from Dhilan007/develop_label

issue #4337: Two fixes for new label:
1. Color and opacity can't take effect.
2. The font size passed to new Label didn't consider 'contentScaleFactor'.