Fix the failing case of the issue #33

If the user add an empty file (or a folder), we should STORE the file
and not DEFLATE it.
Add the notion of version in the index.html file

Fixes #32
Merge pull request #35 from dduponchel/issue32

Add the notion of version in the index.html file
Merge pull request #34 from dduponchel/issue33

Fix the failing case of the issue #33