make the has_many work

[steveklabnik]

https://github.com/steveklabnik/warehouse/blob/master/frontend/app/models/crate.js#L4

I think this is because either

1. I'm not generating the correct JSON for the included data
2. I need to implement the sub-routes anyway

[fsmanuel]

I was going to open a PR but found your solution much better.
I guess https://github.com/steveklabnik/warehouse/blob/master/src/totally_not_a_database.rs#L45 has to be resolved to show more than the last version.

[steveklabnik]

Fixed! #6