TMSS-259: Change format according to Jan Davids suggestions. Change list input to tuples and add caching.

TMSS-259: Add tests for angular separation endpoint. Improve speed on sunrise endpoint by reducing precision.

TMSS-259: Remove optional slash and api_view again from /schemas/ and /station_groups/ because it breaks json ref resolution and more

TMSS-459: Add new endpoint 'angular_separation_from_bodies' and backend logic to calculate distance of a pointing from solar system bodies

TMSS-435: Return json object with sunrise, sunset, day and night times at sun_rise_and_set call, handle multiple stations and timestamps provided as parameters

(cherry picked from commit 3bec3e06)

TMSS-403: Improvement: use build/installed TMSS settings module and LOFARROOT for static files and templates so that django toolbar and frontend work out of the box

TMSS-000: config Access-Control. Our schemas use  url's to other schemas, mainly pointing to our own common schemas with base definitions. We instruct the client to allow fetching those.

TMSS-272: cleaned up SAS/TMSS/src/tmss/tmssapp/validation.py validation code from tmss. Moved remaining clean code into LCS/PyCommon/json_utils.py

TMSS-272: made working example with reusable schemas. Validation works both server-side and client-side in the json-editor widget. For the json-editor widget we need to resolve absolute URL refs as a workaround

TMSS-272: initial version of a way to store common json schema's in a CommonSchemaTemplate model, and inject the  uri's with the base url to make them navigatable

The content type as reported by swagger for subtask/{id}/parset is now text/plain.

It is now possibile to navigate the react frontend (/frontend url).

Added a frontend react app "dashboard" served throug Django backend server (http://127.0.0.1:8000/dashboard/).

TMSS-153: and TMSS-145: fixed populate.populate_lofar_json_schemas according to https://support.astron.nl/confluence/display/TMSS/UC1+JSON
There are now two Task schema and 1 Subtask schema.
Used the schema's, added dataproducts, convert everything to parset.