Improved display of additional data in Exceptionless

...by stripping the property wrappers introduced by Serilog.

I'm aware that the way this is implemented is kind of ugly and limiting, but I don't see a better way.

If a new LogEventPropertyValue implementation ever gets added, the existing code won't break, but the new type will just be displayed (as ugly) as before.

Please have a look at the attached images to see the changes.

__BEFORE__
![before](https://cloud.githubusercontent.com/assets/1156637/3629235/e38d02d2-0e9d-11e4-9f9b-4ea19c6dc1e3.png)

__AFTER__
![after](https://cloud.githubusercontent.com/assets/1156637/3629234/e1554f74-0e9d-11e4-9858-61af29d89c8e.png)