Fix #26
Requested in #26

- Replace `0` by `-` in district table.
- Add `%` to value if value does not equal `0` in district table.
Abstract get municipality info to separate function
Use openstreetmap as baselayer
Merge pull request #29 from Datafable/distr-array

Distr array
Merge pull request #31 from Datafable/integr-leaflet

Use openstreetmap as baselayer, fixes #19
Solve merge conflict
Reorder functions
Refix error