Access url for interventions

* adds access_token as new attribute
* adds generating of access_token
* adds new form
* adds two new routes for sharing an intervention
* adds translation
* adds render_submit to BaseModalForm which triggers rendering the modal footer

konova/forms.py

@@ -109,6 +109,7 @@ class BaseModalForm(BaseForm, BSModalForm):
 
     """
     is_modal_form = True
+    render_submit = True
 
 
 class SimpleGeomForm(BaseForm):