Remove "ADMIN_MEDIA_PREFIX" (deprecated in Django 1.4)

Delete lms/static/admin resources as they are no longer needed
for the admin page as of Django 1.4

Moved two files that were referenced elsewhere:
lms/static/admin/js/jquery.min.js -> lms/static/js/admin/jquery.min.js
lms/static/admin/js/urlify.js -> lms/static/js/admin/urlify.js