Implements tile caching (#46)
Implements tile caching (#46)

- Adds `Cache-Control: "max-age=21600"` header;
- Changes `viewId` to `layergroupId` at tiles route (`/:layergroupId/:z/:x/:y.(:format)`);

ecodigital/DomeGIS,ecodigital/DomeGIS,aparabolica/DomeGIS,aparabolica/DomeGIS,ecodigital/DomeGIS,aparabolica/DomeGIS