DataMapper plugin enabling <b>simple</b> versioning of models.

When a model is versioned, and updated, instead of the previous version being
lost in the mists of time, it is saved in a subsidiary table, so that it can
be restored later if needed.

Please Note!  this gem behaves differently to how AR's :acts_as_versioned
works.  There is currently no multi version storage possible.

Homepage:
http://github.com/datamapper/dm-is-versioned
