define to_dict methods for BaseDocument and BaseField
add test to test to_dict method on Document, EmbeddedDocument and References
Merge pull request #1 from Work4Labs/mvdb/ANA-420/add-to_dict-method

Mvdb/ana 420/add to dict method
add keep_id support in to_dict method
define to_dict methods for BaseDocument and BaseField
add test to test to_dict method on Document, EmbeddedDocument and References
add keep_id support in to_dict method
Merge branch 'staging'
bugfix in BaseDocument.to_dict, we should pass keep_id to dynamic fields