Added create python object class from serializer data.

[nxexox]

Added python class objects from serializer data.
Example:

from rest_framework import serializers

class ExampleObject(object):
 field_one = 10
 def __str__(self):
 return 'ExampleObject(field_one={})'.format(self.field_one)

class ExampleObjectSerializer(serializers.Serializer):
 class Meta:
 to_object = ExampleObject

ser = ExampleObjectSerializer(data={'field_one': 100})
ser.is_valid()
obj = ser.get_object()
print(obj)
# 'ExampleObject(field_one=100)'