Add 'service area' data component

In Tampere, homes are grouped into five service areas. As more homes are using GeriLife, it would be interesting to compare the activity level of different service areas. In order to make the comparison, we first need to add a data component to indicate to which service area each home belongs.

## Task
- add 'service area' component to data model
- include geometry for service area, so it can be displayed on map
- add UI element to link homes with service areas