Allow foreign keys to be strings

[wesleykendall]

Hello, awesome project! I encountered a bug when 'auth.User' was provided as a foreign key. It's valid to have a string path as a Foreign Key, and this change just prints the string path.

I'm not sure of other places in the code that would need to be updated to handle this case. Maybe we can try to update those too?

[vdboor]

Thanks a lot! Glad you like it.

[vdboor]

I'm not sure of other places in the code that would need to be updated to handle this case. Maybe we can try to update those too?

One change would be to use apps.get_model() to fetch the actual class, and print that instead.