Fixed #21177 -- Made resolve_url support relative URLs.

This fixes redirecting to relative URLs with django.shortcuts.redirect.
Fixed #17942 -- Added a JsonResponse class to more easily create JSON encoded responses.

Thanks leahculver for the suggestion and Erik Romijn,
Simon Charette, and Marc Tamlyn for the reviews.
Fixed #21924 -- Added the ability to specify a reverse order for admin_order_field.

Thanks Klemens Mantzos for the report and initial patch.
Fixed #22035 -- reordered migration operations

Now AddField actions appear in operations list before AlterUniqueTogether
actions.

Thanks to SmileyChris for the report.
Added 1.6.3 release note for refs #21566.
Fixed #22049 -- Corrected a misspelling of dimensional
Change analyse (British) to analyze (American).
Fixed #22052 -- Corrected a misspelling of ellipsoid
Merge pull request #2281 from rhcarvalho/ticket_22053

Change analyse (British) to analyze (American).
Fixed typo in docstring.
Moved relative URL handling added in refs #21177 to a better place.

Thanks apollo13: "reverse() shouldn't know about absolute/relative paths."
Fixed typo in test docstring.
Fixed #22018 -- Fixed checks for ModelAdmin.fields not handling sub-lists.

Flatten a level of sublists before checking for duplicate fields.

When given sublists such as:

```python

class FooAdmin(admin.ModelAdmin):
    fields = ('one', ('one', 'two'))
```

The previous code did not correctly detect the duplicated 'one' field.

Thanks to jwa for the report.
Fixed typo in comment.
Fixed two typos.
Fixed #19299 -- Fixed Nullification of Foreign Keys To CharFields

Thanks tunixman for the report and Baptiste Mispelon and
Shai Berger for reviews.
Fixed #18373 - improved handling of Resolver404s from views

When django.core.urlresolvers.resolve was called from a view, failed
and the exception was propagated and rendered by technical_404_response,
the URL mentioned on the page was the current URL instead of the URL
passed to resolve().

Fixed by using the path attribute from the Resolver404 exception instead
of request.path_info. Also cleaned up the exceptions to use standard
named parameters instead of stuffing a dict in args[0]
Fixed #21884 -- Mentioned that exact is the defaut QuerySet lookup type

Thanks to cjerdonek for the suggestion.
Fixed #21765 -- Added support for comparing Context instances
Fixed #21912 -- Improved error message if a view returns None.

Thanks brycenesbitt for the report.