add root url to apu_test_server for all methods

test/api_test_server.py

@@ -23,6 +23,7 @@ def passthrough():
     {'url': request.args, 'body': body, 'header': dict(request.headers)})
   return output
 
-@app.route('/')
+@app.route('/', methods = [
+  'GET', 'POST', 'DELETE', 'UPDATE', 'PATCH', 'OPTIONS', 'PUT', 'HEAD'])
 def rootpath():
   return 'rootpath'
\ No newline at end of file