Refs #8138 -- Added a stealth option to the loaddata command so that the use...

Refs #8138 -- Added a stealth option to the loaddata command so that the use of transactions in loaddata can be disabled. This behavior isn't enabled as a commad line option because it doesn't make much sense, but it can be used when invoking loaddata from another script.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8336 bcc190cf-cafb-0310-a4f2-bffc1f526a37