Feature/plugin runner

Plugins can run now!

I have implemented the runPlugin portion of the test harness. It can run the map function in the dummy plugin "SimpleFeaturesCountPlugin", but runs into an error for the reduce function due to the second parameter type being the general ````Iterable<String>````. It should work if it was declared as ````Iterator<String>```` instead. 

The runPlugin takes a batch of VCF files (A) which are then run through a query, and it also takes in another batch of VCF files (B) that have not been ran with a query. It then runs the map reduce comparing A to every genomic position of B.