* refactors CheckableMixin and RecordableMixin into CheckableObject and RecordableObject
* adds ShareableObject for wrapping share related fields and functionality
* adds share functionality to EcoAccount and EMA, just like Intervention
* adds NewEcoAccountForm
* refactors NewCompensationForm into AbstractCompensationForm so main fields can be reused again
* fixes template bug in account detail view where the amount of deductions has been displayed instead of the available rest
* refactors _generate_new_identifier() into generate_new_identifier()
* refactors get_available_rest() into returning both, the total and relative amount
* improves saving of SimpleGeometryForm()
* adds/updates translations
* refactors documents and file upload to be distributed into different subfolders, depending on the type of document (InterventionDocument, RevocationDocument, ...)
* refactors Document model into AbstractDocument
* subclasses RevocationDocument, InterventionDocument, COmpensationDocument, EmaDocument and EcoAccountDocument from AbstractDocument to provide proper functionality for each
* adds new specialized routes for each new document type (opening, removing)
* drops generic get and remove routes for documents
