Fixed #16949 -- Fixed a small typo in the GIS tutorial and also made some minor…

Fixed #16949 -- Fixed a small typo in the GIS tutorial and also made some minor PEP8 fixes and added some code-block directives while I was at it. Thanks to jgomo3 for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16911 bcc190cf-cafb-0310-a4f2-bffc1f526a37