Generic views

Hi, in my current project we're desperate for a solid working API together with Django and mongoengine. I was looking for a head start, and found your project. 

I managed to tie the existing code in with the generic views, which wasn't supported yet. Also moved the whole serialization part to the fields, with custom Mongo fields for Documents, ListFields, and EmbeddedDocumentFields.

It's all work in progress, but I thought you might want to have a look. Me and my colleagues would be happy to collaborate.

Still have some issues with the default values for the different types. Also would love to get the browsable API working.