add ‘about html5’.
add ‘cocos-utils-for-npm’.
add article getting-started_with-cocos2d-html5.
add article moonwarriors-cocos2d-html5-showcase.
add release note and ‘understand-the-resolution-policy’.
add upgrade-guides-html5.
add articles to catalog list.
Merge pull request #132 from Ivenyang/master

add html5 articles.