* adds support for DELETE method for all relevant objects
* improves get_obj_from_db functionality
* drops custom compensation logic for get_obj_from_db due to improvement of base method
* adds creation tests with minimum data for intervention, compensation, ema and ecoaccount
* fixes bug where empty geometry would not be created properly using the API
* reworks key fetching from POST data, so inproperly stated keys will lead to an error for the API user, instead of silently working and use default data
* adds some logical checks for deductable_surface of eco account creation using api
* fixes bug that would have occured on creating compensations via api
* writes test for sharing using the API
* fixes bug on frontend form where an exception occured on generating a new API token if no token existed, yet
* adds permission constraint (default group) for using the api in general
* fixes default-group-only behaviour for sharing-API, so users can only add new users and not removing them, as long as they do not have any other group membership like registration or conservation office
* changes 'ksptoken' to 'Ksptoken' to match CGI standard for http header keys
* adds support for PUT and POST of Ema
* moves set_responsibility() and set_legal() from Intervention API Serializer into proper Mixins where they belong to
* adds initialize_objects to an abstractmethod of the super class to be implemented in subclasses
* differentiates error messages if intervention does not exist or is just not shared with the user
* adds support for POST of new compensations
* adds shared_users property to BaseObject and Compensation to simplify fetching of shared users (Compensation inherits from intervention)
* extends compensation admin index
* modifies compensation manager which led to invisibility of deleted entries in the admin backend
* fixes bug in sanitize_db.py where CREATED useractions would be removed if they are not found on any log but still are used on the .created attribute of the objects
* adds token checking to AbstractModelAPIView
* adds user accessibility filtering for intervention API v1
* extends fetch_and_serialize() method to take a dict for db filtering instead of a single field and value
* organizes urlnames into supporting formats like "api:v1:intervention"
* adds new app to project
* adds relation between User model and new APIUserToken model
* adds first implementation for GET of intervention
* adds basic code layout for future extension by having new versions
* adds fake-inherited is_ready_for_publish() method to compensation model (not derived from RecordableObjectMixin) to equalize usage of is_ready_for_publish() usage for all data types (compensation can be checked the same way as intervention, ecoaccount or ema)
* adds abstract is_ready_for_publish method to PublishableObjectMixin which needs to be implemented in subclasses
* adds implementation for intervention model
* adds publishable check to rendering report view
* adds/updates translations
* adds tab titles for compensations
* adds/updates translations
* optimizes identifier generating, so that one-digit months will be converted into two digits
