message: Fixes issues with CheckSkuAvailability operation
  1. Changes type of skuName property from Sku to SkuName.
  2. Marks some fields as required.
diff: "Sku": {
  "properties": {
  "name": {
  - "type": "string",
  - "description": "Gets or sets the sku name. Required for account creation, optional for update.",
  - "enum": [
  - "F0",
  - "P0",
  - "P1",
  - "P2",
  - "S0",
  - "S1",
  - "S2",
  - "S3",
  - "S4",
  - "S5",
  - "S6"
  - ],
  - "x-ms-enum": {
  - "name": "SkuName",
  - "modelAsString": true
  - }
  + "$ref": "#/definitions/SkuName",
  + "description": "Gets or sets the sku name. Required for account creation, optional for update."
  },
  "tier": {
  "readOnly": true,
  ],
  "description": "The SKU of the cognitive services account."
  },
  + "SkuName": {
  + "type": "string",
  + "description": "The name of SKU.",
  + "enum": [
  + "F0",
  + "P0",
  + "P1",
  + "P2",
  + "S0",
  + "S1",
  + "S2",
  + "S3",
  + "S4",
  + "S5",
  + "S6"
  + ],
  + "x-ms-enum": {
  + "name": "SkuName",
  + "modelAsString": true
  + }
  + },
  "CognitiveServicesAccount": {
  "description": "Cognitive Services Account is an Azure resource representing the provisioned account, its type, location and SKU.",
  "type": "object",
  }
  }
  },
  + "required": [
  + "keyName"
  + ],
  "description": "Regenerate key parameters."
  },
  "CognitiveServicesAccountEnumerateSkusResult": {
  "skus": {
  "type": "array",
  "items": {
  - "$ref": "#/definitions/Sku"
  + "$ref": "#/definitions/SkuName"
  },
  "description": "The SKU of the resource."
  },
  "type": "string",
  "description": "The Type of the resource."
  }
  - }
  + },
  + "required": [
  + "skus",
  + "kind",
  + "type"
  + ]
  },
  "CheckSkuAvailabilityResultList": {
  "description": "Check SKU availability result list.",
  "description": "The Type of the resource."
  },
  "skuName": {
  - "$ref": "#/definitions/Sku",
  + "$ref": "#/definitions/SkuName",
  "description": "The SKU of Cognitive Services account."
  },
  "skuAvailable": {
  