* adds celery to project
* adds celery background task for updating parcels
* adds parcel calculation to creating of new geometries as well
* tests outstanding!!!
* adds rendering for detail view
* adds new includable html snippet for parcel rendering
* refactors generic includables in konova/ app into konova/templates/includes/...
* fixes bug where parcels have been reused from the database due to wrong model structure
* adds get_underlying_parcels() for Geometry model
* adds get_underlying_parcels() for GeoReferencedMixin models
* fixes bug where missing geometry would lead to an error during geometry conflict check
* removes unused wfs attribute from AbstractWFSFetcher
* adds/updates translations
* extends sanitize db command to remove unrelated parcels and district from the database
* fixes bug where single parcel wfs match would lead to unexpected behaviour
* adds admin interface for parcels and districts
* adds updating of parcels in case of SimpleGeomForm saving
* refactors WFS fetching to proper POST handling
* adds authentication support to WFS handling
* reduces dummy geometry for tests to a small area to reduce test network traffic overhead
* fixes bug in GeometryConflict conflict checking
* WIP: introduces new konova/utils/wfs/spatial holding SpatialWFSFetcher, which can be fed any geometry and it returns found features
* WIP: adds tests for wfs fetching
* updates requirements.txt
