Dirisempty

As soon as this is merged in, it should be only a hop-skip-and-a-jump to complete delete. Fix for GlusterDirectoryIterator is in this commit: https://github.com/FIU-SCIS-Senior-Project-2014-Fall/Java-GlusterFS/commit/9ca094ff645fff0b9325f978d254b375111478a3
There doesnt seem to be any test coverage for the while loop. Otherwise this looks great. Please add the tests for directories with either . or .., and also both.
Thanks!