message: Add schema support for global.json
diff: {
  "fileMatch": "omnisharp.json",
  "url": "http://json.schemastore.org/omnisharp"
  + },
  + {
  + "fileMatch": "global.json",
  + "url": "http://json.schemastore.org/global"
  }
  ],
  "commands": [
  