Post to the API when moving folders and templates

This commit adds logic to:
- take the list of selected folders and templates
- split it into two lists (of folders and templates)
- `POST` that data to the API, to effect the movement of said folders
  and templates

I’ve tried to architect it in such a way that we can easily add more
template ‘operations’ in the future, as we add more forms to the choose
template page.

app/notify_client/template_folder_api_client.py

@@ -24,5 +24,24 @@ class TemplateFolderAPIClient(NotifyAdminAPIClient):
     def get_template_folders(self, service_id):
         return self.get('/service/{}/template-folder'.format(service_id))['template_folders']
 
+    @cache.delete('service-{service_id}-template-folders')
+    @cache.delete('service-{service_id}-templates')
+    def move_to_folder(self, service_id, folder_id, template_ids, folder_ids):
+
+        if folder_id:
+            url = '/service/{}/template-folder/move-to-folder/{}'.format(service_id, folder_id)
+        else:
+            url = '/service/{}/template-folder/move-to-folder'.format(service_id)
+
+        self.post(url, {
+            'templates': list(template_ids),
+            'folders': list(folder_ids),
+        })
+
+        self.redis_client.delete(*map(
+            'template-{}-version-None'.format,
+            template_ids,
+        ))
+
 
 template_folder_api_client = TemplateFolderAPIClient()