add an example that runs wordcount over file datasets

simple example to read and write files. 
- a service that can upload/download files
- a mapreduce that reads/writes the same files, with runtime arguments to specify the paths

I am open to renaming this, if you have a better suggestion. 
I don't know what for the <p> should be. A <ul> is also a paragraph block. But agreed that the first </ul> is wrong. IntelliJ generated this for me :)