Single character command line option variants missing

[mbreissi]

The option set as currently defined does include single character variants of the options (e.g., -b for broker). Suggested fix is to replace current option set definition in Configuration.cs with:

            var options = new OptionSet
            {
                {
                    "b|broker=", val => { BrokerUrl = val; }
                },
                {
                    "t|token=", val => { Token = val; }
                },
                {
                    "l|log=", val => { LogLevel = LogLevel.ParseLogLevel(val); }
                }
            };