Fixed #21530 -- Prevent AttributeError in default URLconf detection code.

Thanks to @dmyerscoug for the report and original patch
and to @alasdairnicol for the added tests.
Added fix for #21530 to 1.6.1 release notes.
Fixed #21572 -- Added unit test for django.utils.text.normalize_newlines.
Merge pull request #2045 from vajrasky/ticket_21572

Fixed #21572 -- Added unit test for django.utils.text.normalize_newlines...
Fixed #21568 -- Added missing ModelMultipleChoiceField to_python method

Thanks dibrovsd at gmail.com for the report and Simon Charette
for the review.
Fixed #21551 -- Reenabled loading fixtures from subdirectory

This was a regression in Django 1.6 that was only partially
restored in 839940f27f.
Thanks Jonas Haag for the report.
Fixed #21555 -- Made ValidationError pickable.

Thanks trac username zanuxzan for the report and original patch.
Added extra newline for flake8.
Removed unneeded string normalization in contrib.admin

With Python 2.7 and up, named parameter keys are not limited to
bytestrings any longer. This mainly reverts 3bd384aa626.
Fixed #21573 -- Improved performance of utils.text.normalize_newlines.
Fixed #18531 -- Deprecated Geo Sitemaps

I've chosen a quick deprecation path, as Geo Sitemaps themselves
are deprecated from some time now.
Renamed first argument of class method to cls
Merge pull request #2050 from maurycyp/master

Renamed first argument of class method to cls