Generated AAI Swagger file has schema violations

Generated AAI Swagger file has schema violations

Fixes for violations
- provide a valid host (localhost) for the `host` key
- remove `example` keys for parameters
- remove `also requires` property from definitions

Other changes
- remove the license header from description and add it instead as a yaml comment (like we do it for any other file)
- remove the `contact` block since it does not contain actual contact information
- remove the reference to the AT&T wiki for the default response codes
- remove `description: n/a` values in parameters that are set when there is no description available

Issue-ID: AAI-3611

Signed-off-by: Fiete Ostkamp <Fiete.Ostkamp@telekom.de>
Change-Id: I057f7f3a49a861891c49b52bff80e5a9810f18a7