Dirk fixes layer groups

Branched from https://github.com/nens/lizard-client/pull/119

layerGroup.getData(geom) returns a promise that is notified with data and resolved with `true`. So the Area, Point and Line Ctrls should have a promise.then(`function when completed either with true or false, meaning succesfull because you got all the data thats there or false when something went wrong`, `function that executes when the whole promise went wrong (maybe just specify null)`, and a `function that is executed when a new part of the data for that layergroup comes in and puts this data on the right part of the scope for display in the box`)

- [x] AreaCtrl should ask layergroup.getData and not interfere with individual layers anymore.
- [x] LineCtrl should ask layergroup.getData and not interfere with individual layers anymore.
- [x] PointCtrl should ask layergroup.getData and not interfere with individual layers anymore.
- [ ] Refactor pointCtrl (used to be: pointObjectCtrl)