Documents removing

* adds generic modal rendering using package django-bootstrap-modal-forms
* adds document file removing from hard drive
* adds translations

templates/modal/modal_form_script.html

@@ -0,0 +1,18 @@
+{% comment %}
+    Taken from https://github.com/trco/django-bootstrap-modal-forms
+
+    isDeleteForm refers to reloading the whole page after submitting the form in our case.
+
+{% endcomment %}
+
+    <script type="text/javascript">
+    $(document).ready(function() {
+        $(".{{btn_class}}").each(function () {
+            $(this).modalForm({
+                    formURL: $(this).data("form-url"),
+                    isDeleteForm: {{modal_reload_page}},
+                }
+            );
+        });
+    });
+    </script>