Provide means to seed database with Cargos in transit, Routes, etc.

[paulrayner]

Currently the database is seeded by sample_data_spec.rb, which is a total hack. This should be a rake task or something. Plus, it needs to be more than just one cargo, and more than just a handful of locations etc.

The Java and .NET sample apps have a button, but perhaps there is a better way to expose this as a kind of "behind the scenes" thing.