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.

Use PYTHONDONTWRITEBYTECODE=1 on tox environment

This fixes bad marshal data errors after running
tests with tox and later running tests manually
via runtests.py. Fixes #1957

Maintain order of views on router for api root view.

wider compatability.

Add docs regarding linking third party packages

Add djoser to authentication docs

Update links in 2.4-announcement.md

The links to Django Rest Framework pages were 404ing because the URLs include a slash.

[templates/rest_framework/base.html] Separate IDs for POST and PUT forms

[templates/rest_framework/base.html] Separate `object-form' and `generic-content-form' IDs for POST and PUT forms

Signed-off-by: Anton D. Kachalov <mouse@yandex-team.ru>

Correctly propagate cloned_request for OPTIONS

Remove patterns and strings from urls in tutorial.

Update to fix pending changes in #1507

Fix missing CSRF exemption on viewsets

Clarify "raised inside REST framework"

DefaultRouter support for viewsets without an implemented default action

Update authtoken latest Django 1.7 migration

I ran into an issue today where I was not seeing the rest_framework.views.exception_handler do what I thought it should be doing. It turned out that I had imported View from rest_framework.views rather than importing APIView from rest_framework.views. The phrase "raised inside REST framework" was confusing as I was debugging this issue. I was unsure if that meant that I could raise those exceptions in my code or if it had to originate from within framework code.

I'm not sure if the proposed wording is ideal, I just wanted to point out what I found to be confusing.

add wq.db router and django-rest-pandas renderers

Add Third Party Resources Topic section