* adds user/includes/contact_modal_button.html for calling contact data of a user
* adds user contact modal to intervention detail view
* adds translations
* adds modal form for adding payments
* generalizes generic_table_form.html for table-form-like usage in modal_form.html
* adds css enhancements for focused input fields
* adds BaseModalForm as specification to BaseForm, which inherits the BSModalForm class as well
* adds translations
