LoggerFactory AutoFac resolution fails

[mathewc]

Currently if you create an invalid host configuration (e.g. setting "functionTimeout": "00:50:00") it will cause ScriptHost initialization to fail early with a validation error. Requests to admin endpoints will subsequently fail, due to dependency injection resolution failures in this line of code. In this case the host instance is null, so this results in a null ref, and the ILoggerFactory fails to resolve. This causes AdminController creation to fail, and the portal cannot hit the status endpoint to show the validation error that the customer needs to see.

With these changes, the admin/host/status endpoint can correctly return the error:

{
  "state": "Error",
  "version": "1.0.0.0",
  "errors": [
    "Microsoft.Azure.WebJobs.Script: FunctionTimeout must be between 00:00:01 and 00:10:00."
  ]
}