message: Add ErrorResponse to "AddIntent" post
  * Add ErrorResponse to "/apps/{appId}/versions/{versionId}/intents" post
  * Adjust enums of /definitions/ReadableType
  Add "Closed List Entity Extractor "to enum list
  Add "Regex Entity Extractor" to enum list
diff: "schema": {
  "$ref": "#/definitions/GuidResponse"
  }
  + },
  + "default": {
  + "description": "Error Response.",
  + "schema": {
  + "$ref": "#/definitions/ErrorResponse"
  + }
  }
  },
  "produces": [
  "Prebuilt Entity Extractor",
  "Intent Classifier",
  "Pattern.Any Entity Extractor",
  - "Regular Expression Entity Extractor"
  + "Regular Expression Entity Extractor",
  + "Closed List Entity Extractor",
  + "Regex Entity Extractor"
  ]
  },
  "HierarchicalEntityExtractor": {
  