Added integration tests for dealing with idiffing compressed folder trees

  Since we want to deal with compressed trees when performing diffs, tests
  were added to get that functionality.
Added diff test files
Added diffing of archives functionality

  With this commit, the code can now correctly create diffs from two compressed
  archives and generate a compressed diff. The test files were also updated
  since they had internal problems with the path.
Merge pull request #6 from endlessm/diff_on_files

Diff on files