JSON output

[lbdm44]

As a consumer of ember-cli-checkup, I should be able to output the results as JSON so that I can easily consume them by an ETL process.

• Create a ResultWriter class which would be responsible for outputting the result of all tasks.
• ResultWriter should have a toConsole and toJson method
• Delete ResultConsoleWriter in favor of ResultWriter

Potential JSON result:

   "tasks":[ 
      { 
         "types":{  }
      },
      { 
         "tests":{  }
      }
   ],
   "dependencies":{  },
   "type":"application",
   "name":"overly-complex-ember-storefront",
   "version":"0.0.0"
}```