Serializers should be format-specific

[monokrome]

A Serializer should be defined in a way that is format-specific, instead of representing a "has-many" relationship in one Serializer, the current supported Serializers should be composed of many Serializer objects.

Right now, if I wanted to use two third party Serializers, I need to create some middle-ground object that merges them together. The real need is to be able to treat serializers much like middleware.

TASTYPIE_SERIALIZERS = [
    'tastypie.serializers.json.Serializer',
    'tastypie.serializers.xml.Serializer',
    'tastypie.serializers.yaml.Serializer',
    'thirdpartylibrary.serializers.msgpack.Serializer',
    'thirdpartylibrary.serializers..Serializer',
    'myproject.serializers.protobuf.Serializer'
]

If you need to define Resource-specific Serializer objects, you should be able to define them as such:

from tastypie.serializers import json, xml

class MyResource(ModelResource):
    class Meta(object):
        serializers = [
            xml.Serializer,
            json.Serializer,
        ]