Courtesy default dummy security policy

[opoudjis]

Do we define a default, dummy security policy in the OpenAPI at the root of the document? We don't have to, but we could include Basic HTTP SIF as a courtesy to novices:

Error :: security-defined rule :: Every operation should have security defined on it or on the root level.:

800 of the 11398 errors generated.

[opoudjis]

Put in basic authentication, as a starting point security policy.

[joerghuber]

Added SIF_HMACSHA256 and Bearer as additional security schemas.