Enum array support

[bwbroersma]

Enum looks nice in SwaggerUI, enum arrays do not.
Here the changes that work for me for nice SwaggerUI output, but it might not be correct for the OpenAPI standard: code diff

[bwbroersma]

Ok the previous commit / provided solution is not the correct way to do it, this will also result in an
Example Value

{
  "the-enum-array-field": "first-value"
}

were we would want more something like

{
  "the-enum-array-field": ["first-value"]
}

[bwbroersma]

The correct Swagger to output (according to the docs) is:

{
  "format": "schema.typename[]",
  "type": "array",
  "items": {
    "type": "string",
    "enum": ["first-value", "second-value"]
  }
}