* adds error message on intervention view if a payment has been added but no document has been uploaded yet
* adds same check to quality checker, meaning no intervention can be recorded which has a payment but no document
* adds trigger for sending data to egon on uploading a document in case of an already existing payment
* adds translations
* refactors intervention/forms and ../modalForms into individual files in separated packages
* forms.py has been renamed into intervention.py, now can be found as intervention/forms/intervention.py
* modalForms.py has been split into individual files living in modals package, can be found as intervention/forms/modals/...
