Many code changes to make everything work with Path and XmlInputFormat. Completes milestone 2.

The existing code works with Files. Hadoop works with [Paths](http://hadoop.apache.org/docs/r2.3.0/api/org/apache/hadoop/fs/Path.html) and [FileSystem](http://hadoop.apache.org/docs/r2.3.0/api/org/apache/hadoop/fs/FileSystem.html) which provide an abstraction over files and file systems. That is to say, Hadoop encapsulates the stuff about distributed or local files and files systems and lets us work with Paths and InputFormats. This pretty much sums up most of the stuff in the commits.

Other than that, I added the XmlInputFormat. I tested with run-extraction-test and everything works. DistRedirectsTest passes. I added some docs too.

Please note that I have taken care to make the commits in a specific sequence. If you make your way from commit 4b9745f to commit d08417f it'll be easier to understand what's going on.

Also, it's worth a mention that you'll need to clone https://github.com/nilesh-c/extraction-framework , switch to the **fromxml** branch and run `mvn install` before building this repo on this branch. I've made a PR to extraction-framework with the changes in **fromxml**.
This line means that DistDisambiguations is not thread-safe. Example: Thread A calls load() with a certain value for hadoopConf. This value is stored in hadoopConfImpl and should be used while thread A is executing load(). But then thread B also calls load() with a different value for hadoopConf, and this value is stored in hadoopConfImpl. Thread A still executes load() but now uses B's value of hadoopConf.

I think you should get rid of the field hadoopConfImpl. I can think of two ways to achieve this:

Either make hadoopConf an implicit parameter:

```def load(..., lang : Language)(implicit hadoopConf: Configuration) : Disambiguations```

The Scala compiler will then use this implicit value where needed.

Or use ```hadoopConf``` explicitly where it's needed, that is, expliticly call ```wrapPath``` wherever you call ```FileLike``` methods on an expression of type ```Path```.