Merge pull request #8139 from tttreal/label-getStringNumLines-bugfix

[CCLabel] Apply updateContent() for getStringNumLines() when Label is dirty
[ci skip] Update CHANGELOG
[ci skip]Update Authors
[AUTO]: updating luabinding automatically
Merge pull request #8155 from CocosRobot/update_lua_bindings_1411627694

[AUTO]: updating luabinding automatically