Apicast management API is not validating any JSON, sent through `POST` request.
Malformed JSON may even cause that gateway will crash and not recover.

When non valid config JSON has been send: there will be no error message admin, but instead ok message.

for example:

Crash:

asdsadsadsadaa

��

Also when you send in configuration file two different versions of the same api, the second one configuration will apply -> I would suggest that this should be also validated and return error, to user is not confused.

Also it gave us some time to realize, that we have to send the specific configuration that we downloaded from admin portal through UI, not just by pasting json, but formatted it this way:

{
  services: [
     <CONTENT_OF_SPECIFIC_VERSION>
  ]
}

When we just send only that content of the file, it responded ok, but configuration wasn't changed. (We know how to solve this problem but OK message is confusing.)