Tweaked the Admin add/change page so that "save" is still the highlighted

too look like the default button and it actually operates as the defaut
(previously "save and add another" was the default action, which confused
people if you hit the save button and it looked like your work was eaten by a
grue).

Fixed #7272. Patch from Jannis Leidel.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8501 bcc190cf-cafb-0310-a4f2-bffc1f526a37