Provide sample shared data directory with release

[ivilata]

As mentioned in #55, many files related with user-level configuration will end up in the shared data directory, and their location and naming will be important. To ease its use and avoid errors, we may provide an archive of the directory with each release. For instance, an ereuse-data-X.Y.Z.tar.gz may contain:

• ereuse-data, to be shared with the server VM
• ereuse-data/config.ini, with the default configuration for this version of DDI
• ereuse-data/images, an empty directory for installation images (FSArchiver and others)
• ereuse-data/isos, for bootable ISOs
• ereuse-data/isos/eReuse.iso, the eReuseOS ISO for this version of DDI (me may or may not publish it separately)
• ereuse-data/isos/DebianLive32.iso, another ISO for installation (not to be distributed, just an example of a file that the user may drop in)

This issue depends on #55.

[ivilata]

Already implemented in data-directory-55, plus a PXELINUX boot entry template for each ISO image file.

I'm closing this since the development is already happening in #55.