Fix/ Refactor math/Random.js

There was a minor bug in it:
See http://jsbin.com/sewupumifa/2/edit?js,console

And also some redundancy in `.integer` and `.range.`.

I think renaming `.integer` and `.range` would make sense. Something like I think something like `.integerRange` and `.floatRange` would make sense, since both **can** return an array.