Support Django Guardian 1.3

Upgrade guardian support to 1.3. #3165

increase serializer compatibility to django 1.8

change SortedDict to OrderedDict + fix list and tuple concatination

Update release script.

Update 2.4 docs url for real

Missed the important hunk

i ran into this issue when using v2.4 with django v1.8. (i didn't previously read it isn't supported)
It's not in the release notes but django.db.model.Options many_to_many() now returns an ImmutableList which is really just a tuple with a bunch of warnings and hooks on it.

if we don't make this typecast change we get the following error

TypeError: can only concatenate tuple (not "list") to tuple

I'm not sure if this change is appropriate and not sure what, if any, additional tests to include with this .

I attempted to test this but must be doing something wrong.
Every test fails when trying to use cursor. most of the errors I get are

 Failed: Database access not allowed, use the "django_db" mark to enable

i followed the instructions here.
https://github.com/tomchristie/django-rest-framework/blob/version-2.4.x/CONTRIBUTING.md

Update 2.4 docs url

Point to version 2 docs instead of the latest and greatest docs.

Backport 7872d0ac to 2.4.x

Fixed get_component method in Field to get working with subclassess of collections.Mapping

Set up serializer fields lazily on-demand.

Fix follow does not work on get of APIRequestFactory

Frameworks throws AssertionError saying you cannot set required=True and...

docs(api-guide/authentication): updated to reflect new standards in Django 1.7

Based on the [new documentation](https://docs.djangoproject.com/en/dev/topics/auth/customizing/#django.contrib.auth.get_user_model) for Django 1.7 we should now use:

```python
@receiver(post_save, sender=settings.AUTH_USER_MODEL)
```
instead of:

```python 
@receiver(post_save, sender=get_user_model())
```
because `get_user_model()` only works once Django has imported all models. Otherwise you'll get: 

```python
django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.
```
When trying to start your sever after adding token authentication.

From the Docs, ( linked above as well ) :
>New in Django 1.7:
>When connecting to signals sent by the User model, you should specify the custom model using the AUTH_USER_MODEL setting.