Upgrade django-pagination to a "maintained" fork

Closes #3664

The package `django-pagination` got unmaintained, so a fork by Linaro
was created at https://github.com/zyga/django-pagination and got
unmaintained again (zyga/django-pagination#42).

Now, there is another fork at https://github.com/pydanny/dj-pagination)
that contains more compatibility releases. So, I'm upgrading to this one.

Author: humitos

readthedocs/settings/base.py

@@ -71,7 +71,7 @@ def INSTALLED_APPS(self):  # noqa
             'django.contrib.humanize',
 
             # third party apps
-            'linaro_django_pagination',
+            'dj_pagination',
             'taggit',
             'guardian',
             'django_gravatar',
@@ -131,7 +131,7 @@ def USE_PROMOS(self):  # noqa
         'django.middleware.csrf.CsrfViewMiddleware',
         'django.contrib.auth.middleware.AuthenticationMiddleware',
         'django.contrib.messages.middleware.MessageMiddleware',
-        'linaro_django_pagination.middleware.PaginationMiddleware',
+        'dj_pagination.middleware.PaginationMiddleware',
         'readthedocs.core.middleware.SubdomainMiddleware',
         'readthedocs.core.middleware.SingleVersionMiddleware',
         'corsheaders.middleware.CorsMiddleware',

requirements/pip.txt

@@ -56,6 +56,7 @@ django-textclassifier==1.0
 django-annoying==0.10.1
 django-messages-extends==0.5
 djangorestframework-jsonp==1.0.2
+dj-pagination==2.3.2
 
 # Docs
 sphinxcontrib-httpdomain==1.4.0
@@ -70,5 +71,4 @@ django-cors-middleware==1.3.1
 nilsimsa==0.3.7
 
 # Pegged git requirements
-git+https://github.com/zyga/django-pagination.git@86caf15#egg=django_pagination-dev
 git+https://github.com/alex/django-taggit.git#egg=django_taggit-dev