add support IE8 by default

- add `internalForEach` http://youmightnotneedjquery.com/#array_each **for IE8**
- replace `[].forEach` with `internalForEach` where needed
- edit tests to use `ki.ie8.min.js` and `ki.extend.min.js`
- edit tests to use `$(function() {})` instead of `DOMContentLoaded` and etc.
- change `$.each()` callback return item as 1st argument, index as 2nd such as [].forEach
  + breakable change? maybe, but thats more correct
  + and because more people needs item, not key/index, wtf. why to write it when u dont need it.

now
```js
$.each(arr, function(item, index){
  log(item, index);
})
```

before
```js
$.each(arr, function(index, item){
  log(item, index);
})
```