Fixed #14130 -- Made manage.py error reporting more useful when the...

Fixed #14130 -- Made manage.py error reporting more useful when the settings.py file triggers import errors (in new projects). Thanks Setok for the report, mk and steph for their work.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15522 bcc190cf-cafb-0310-a4f2-bffc1f526a37