finished UBA NRT with the new database structure using the REST API (also added minor fixes to REST API and NRT changelog behaviour)

#17: REST APIs to changelog tables are build; #9: patch API for stationmeta creates a separate changelog entry for every field changed in the metadata

#4: bug fix done for nested stationmeta (inside timeseries record); still left to do: clean up of code and adapting pytests

#4: nested download was extended for timeseries; TBD: showing nested station information is not working yet; also changed programme from many-to-many to 1:n

#3,#4: nested uploads/downloads using controlled vocabulary; still to investigate: how to load enum_tables at beginning (this commit is a workaround)

#3: toar_controlled_vocabulary is used for downloading timeseries, pytests are added for timeseries; not yet working: how to show human readable fields inside nested models (how is this 'conversion' done automatically?)

almost done: using human readable controlled vocabulary for upload; TBD: using human readable controlled vocabulary for download, adapting pytests

#4: nested upload for stations done; TBD: more testing (esp. pytest), use controlled vocabulary (related to #3)

#4: defined association tables also in models; now using one base for the whole app 'toardb'; this has now also to be adapted to test_base

#4: nested upload/download for roles (timeseries) working in production and pytest (uploading codes not human readable version)

#4: a typo made my days and nights long; after git crash do another upload; now detangling models_core and models_role again (different source code files)

#4: code completely messed up, but nested upload working; nevertheless download is NOT returning the nested view

#1: pytest for uploading data with no_autoflush now working; added timeshift_from_utc to data insertion; added error message if trying to insert duplicates

#1: pytest for data established; renamed date_time to datetime; needed 'no_autoflush' in timeseries queries

created ONE toardb app, also adapted pytests for toardb app (still very last test will throw an error for teardown; inserted example for url percent encoding