Support org versions > 8 (only) using a new style exporter

This branch has been lying around for a long while, and I would like this to replace the code in the master. 

The code on this branch removes some of the hackish code currently on master, using an ox-wp exporter, making the code much cleaner and hopefully much more maintainable. 

It would be great if some of us can beta test this branch before, merging this into master. 

Also, a weak attempt at adding some form of test coverage has been made.  Any help in this direction would be greatly appreciated!