Command line mode

Opening new PR to replace #71
@davidfowl @abnanda1 
`LogAgent` and `LogWorker` are async methods but don't have awaits. It will/should result in the warning CS1998 (something like "async method lacks await"). Why not change the implementation to `await Console.WriteLineAsync(format, arguments);` or even remove the `async` keyword and change the implementation to `return Console.WriteLineAsync(format, arguments);`