Add extend method for cc object

I think we should add `cc.extend` method which help developer easily merge attributes of object to another object without using extra library like underscore
[Fix] - Polyfill for bind

In case of multi params from `bind` function, it leads wrong case because we only accept one param in `bind`. I think you should we `bind` function polyfill which provide by Mozilla [Function bind](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind)
[Fix] - Facebook pluginx dialog

There is a case when method is 'apprequests' and we don't need `href` attribute in `info`. If we check `info` doesn't have `href` attribute, Facebook Ui for 'apprequests' will be not trigger
Merge pull request #2207 from pandamicro/develop

Update docs for RC3 release
Merge pull request #2201 from MQuy/patch-3

[Fix] - Facebook pluginx dialog
Merge pull request #2199 from MQuy/patch-1

Add extend method for cc object
Closed #5879: Fixed a bug of cc.Menu that its item's touch priority is different to cc.eventManager
Merge branch 'develop' of git://github.com/cocos2d/cocos2d-html5 into Iss5879_ccMenu
Merge pull request #2209 from dingpinglv/Iss5879_ccMenu

Closed #5879: Fixed a bug of cc.Menu that its item's touch priority is different to cc.eventManager
Merge pull request #2200 from MQuy/patch-2

[Fix] - Polyfill for bind
Consider using function to check type of variable

I think we should we function to check type of variable like underscore or lodash to make it more flexible or easier to test
Issue #5885: Micro message browser does not support the error event of audio
Issue #5884: Micro message browser does not support the error event of audio
Merge pull request #2211 from VisualSJ/5884

Issue #5884: Micro message browser does not support the error event of audio
Merge pull request #2210 from MQuy/patch-1

Consider using function to check type of variable
Fixed #2210: replaces typeof with cc.isXXXX
Merge pull request #2212 from dingpinglv/Iss2210_CheckType

Fixed #2210: replaces typeof with cc.isXXXX
Issue #5888: Type resolution adaptation
Issue #5888: Type resolution adaptation
Merge pull request #2213 from VisualSJ/5888

Issue #5888: Type resolution adaptation