Factor testing setup as Test::DBIC::Roo

[racke]

I think that the testing setup in Interchange6::Schema is very useful and I'm going to factor it out as Test::DBIC::Roo. So I can apply it to other schemas I'm working without copy & waste.

[racke]

Ripped out the relevant commits and put them into a new repository: https://github.com/racke/Test-DBIC-Roo.