Add 5 Chinese tutorials.
modify original links.
Merge pull request #126 from Ivenyang/master

add 5 tutorials.
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add a tutorial like flappy bird.
Merge commit 'dd747e83242f1cc1d17d0852eb815cebc931909c'
modify file name.
Merge pull request #127 from lorrylockie/patch-1

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fixed #4049, Update document of “How to use httpclient” to Cocos2d-x 3.0
Merge pull request #128 from u0u0/master

fixed #4049, Update document of “How to use httpclient” to Cocos2d-x 3.0
issue #3960, Menu tutorial part 1.
issue #3960, Menu tutorial part 2 & part 1 link fix.
fixed #3960, Menu tutorial part 3.
issue #3959, sprite tutorial part1.
issue #3959, sprite tutorial part2.
add articles of ‘about cocos2d-x’.
fixed #3959, sprite tutorial part3.
add articles about ‘cocos2d-x basic concepts’.
Merge pull request #129 from Ivenyang/master

add article and tutorials.
Merge pull request #130 from u0u0/master

add sprite-tutorial & menu-tutorial