Update to FX 4.5, Demo app, auto log some attributes

Hi there Joe. Thanks for your work on this. I've made some further improvements for your review.

* Updated to FX 4.5 and pulled latest nuget packages (left nlog at v2)
* Automatically log exceptions as a rich JSON object
* Automatically log Hostname and SequenceID
* Added ability to set application name 
* Updated readme

Let me know what you think.
cheers
Neutmute