File and stream assertion 

Is there possible to port [FileAndStreamAssertionsExamples](https://github.com/joel-costigliola/assertj-examples/blob/master/assertions-examples/src/test/java/org/assertj/examples/FileAndStreamAssertionsExamples.java) to FluentAssertion?

Assertion two files are (not) same with **diff feature** is important.

Diffs respecting xml structs are welcome