Represents a custom enum type definition in a JSON schema.

JSON Schema:

"color": {
  "description": "A set of colors",
  "default": "green",
  "type": "string",
  "enum": ["none", "green", "orange", "blue", "yellow", "red"]
}

Resulting in the Elixir representation:

%EnumType{name: "color",
          description: "A set of colors",
          "default": "green",
          path: URI.parse("#/color"),
          type: "string",
          values: ["none", "green", "orange",
                   "blue", "yellow", "red"]}