@Override
          public int compare(DiskStorage.Entry lhs, DiskStorage.Entry rhs) {
            return lhs.getId().compareTo(rhs.getId());
          }
Inserts 3 files with different dates. Check what files are there. Uses an iterator to remove
the one in the middle. Check that later.

@throws Exception
imagepipeline-base/src/test/java/com/facebook/cache/disk/DefaultDiskStorageTest.java