Removed a mutable default param in Serializer.serialize().

I haven't seen this pop up explicitly as a bug in code; only noticed it
through code inspection.
Docs were importing json twice without alias

Now the example is working because pjson is an alias
to native json Python library.
It should not rename standard packages

It was giving an alias to json that is not a good pattern.
Merge pull request #1094 from mauricioabreu/master

Docs were importing json twice without alias
Update authorization.rst

Small grammar fix.
Merge pull request #1105 from jmahmood/patch-1

Update authorization.rst
Typo
Merge pull request #1106 from rolandgeider/master

Fix typo in authorization.rst
Update cookbook.rst

I think the 'alternative approach' is in the wrong place
import slugify from django.utils.text
Merge pull request #1110 from gutworth/patch-1

import slugify from django.utils.text
Fixing base class reference
Fixing base class reference
Merge pull request #1111 from eamonnfaherty/master

Fixed base class reference and changed attribute name
Added section about httpie

tastypie plus httpie make up a very nice combination for interacting with RESTful web services.
Merge pull request #1117 from nikos/patch-1

Added section about httpie
import unquote within try/except block to support both python 2&3
Merge pull request #1120 from copelco/gis-python3

Add Python 3 support in contrib.gis
Fixed biplist URL
Merge pull request #1121 from qrilka/patch-1

Fixed biplist URL