Properties Case Class inside Feature instead of JSObject

[zmays]

Thanks for the lib, has come in quite handy.

One thing I came across when using the lib is the desire to describe a case class for the particular properties I deal with.

relevant snippet here:
case class Feature[C](geometry: Geometry[C], **properties: Option[JsObject] = None**, id: Option[JsValue] = None, bbox: Option[(C, C)] = None) extends GeoJson[C]

With the way it is now, working with properties if you need to is a little difficult, and one has less control on the writes - if properties was a generic passed in I could describe the read and write functionality needed.

I'm happy to contribute if you think this makes sense assuming you don't already have ideas on how to handle this that I am missing.

[guizmaii]

Hi,

I'm working on this in the following PR : #19