Merge from vendor branch TNF:

Merge from vendor branch TNF:
Importing ruby-dm-core 1.0.2.

This is core part of ruby-datamapper.

An Object/Relational Mapper for Ruby.

DataMapper sports a very accessible code-base and a welcoming community.
Outside contributions and feedback are welcome and encouraged, especially
constructive criticism. Make your voice heard! Submit a
ticket[http://datamapper.lighthouseapp.com] or
patch[http://datamapper.lighthouseapp.com], speak up
on our mailing-list[http://groups.google.com/group/datamapper/], chat with us
on irc[irc://irc.freenode.net/#datamapper], write a spec, get it reviewed, ask
for commit rights. It's as easy as that to become a contributor.