Added a FileField and an ImageField

Added note about MultipartParser only supporting file uploads and Django's default upload handlers.

support for custom page size per request

./mkdocs.py -p opens a preview in your default browser

./mkdocs.py -p opens a preview in your default browser. Tested on Mac, but should work on windows and Linux as well.

Fixes #417

No type checking in .restore_fields()
Added missing BytesIO import.

Location header when Creating a Resource with HyperlinkedIdentityField

added description how to use the auth token

fixed some typos

and adding myself to auhtors file

Adjusted generics, mixins and serializers to take a `files` arg where applicable.

added it in first commit but after third it became useless.

Location header is set just, if there is a Location field on the
serializer.

after changing the headers storing of reponse

reponse didnt handle any headers at all. Accepts now a dict of headers
and sets those properly

when creating a Resource with HyperlinkedIdentityField of any name

Fixes #380