I'm happy to do `url.split("/").last`, but we still need a way to remove the extension (we can't `cd` into a tarball). I tried [Files.getNameWithoutExtension][Files] from Guava but this doesn't remove all of `.tar.gz` (just the `.gz`). Thus, I was splitting up to the first `.` and then `cd`ing into a directory that started with whatever I grabbed + `*`. Make sense? Happy for suggestions.

Also, I'll assume you want me to update MesosSchedulerBackend.java to use `url.split("/").last` too.  

[Files]: http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/Files.html#getNameWithoutExtension(java.lang.String)