Add Iskeyword option

[paraduxos]

I have set iskeyword+=- so viw inside foo-bar is one word. But I would like easymotion to treat foo-bar as separated word.

So I come up with

let g:EasyMotion_is_not_keyword = "-"

Ps. I also tried read manual about EasyMotion Iskeyword but I was confused about the propose of that function (I'm not native English). I end up create this.