fixed #3278, init
add title to each chapter
fixed #3278, add title to each chapter
fixed 3278, finish the tutorials
fixed #3278, finish chapter 4 of cocos2d-html5 tutorial
fixed #3278, add download link
Merge pull request #9 from leafsoar/master

fixed #3283, add document
Merge pull request #8 from andyque/master

fixed #3278, finish chapter 4 of cocos2d-html5 tutorial
Add the sample structure in content & catalog for IronCity tutorial
Merge pull request #10 from walzer/master

issue #3286, add sample structure for IronCity tutorial