Feature/add json service for geometries

Created by: ghost

REST-API:

• geojson for boundingbox and excerpt (with permissions)
• javascript update to use consume api

Ran tests with RUN_E2E=true ./test.sh, all green.

Tested manually:

• back and forth in frontend between exiting and new excerpt

Reviewed by:

• @das-g
• @wasabideveloper

Closes #239 (closed)