Add example that reads a local file, writes to a DFS path provided by th...

...e user, reads the file back from the DFS, and compares word counts on the local and DFS versions. Useful for verifying DFS correctness.
the style here is confusing. This should be rewritten as
```
fileContents.flatMap(_.split(" "))
  .flatMap(_.split("\t"))
  .filter(_.size > 0)
  ...
```