Fixed #9092 -- Improved validation of app/project names by...

Fixed #9092 -- Improved validation of app/project names by startapp/startproject so that it doesn't allow names to start with a number.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9043 bcc190cf-cafb-0310-a4f2-bffc1f526a37