Stiivi/bubbles — pull request #17 by ericgazoni (2014-05-08 14:38:33+00:00)
Title: add support for XLSX file format

I added support for xlsx file format, I just copied the interface from XLS and replicated the bits I found in the tests. I also updated the docs to mention the new dependency.
All tests pass for me, though not everything had a test in the xls version.