Provide spaces and maxes as static properties

`spaces` and `maxes` are useful information, which can be used in automation and reducing duplicated code of components depending on color (like color pickers, [color-range](https://github.com/dfcreative/color-range) etc.). For now they’re declared within `setValues` scope, which makes them inaccessible from the outside.

This fix makes `spaces` and `maxes` available as static properties `Color.spaces` and `Color.maxes`.

Performance is equal, as [test](http://jsperf.com/static-members-vs-scope-variables) shows.