Improved performance of STATIC_URL and MEDIA_URL setting access.
Improved performance of STATIC_URL and MEDIA_URL setting access.

Run `add_script_prefix()` on first access, rather than on every time. 
pauloxnet/django,manhhomienbienthuy/django,googleinterns/django,solarissmoke/django,felixxm/django,django/django,elena/django,koordinates/django,pauloxnet/django,blighj/django,solarissmoke/django,dsanders11/django,apollo13/django,apollo13/django,takis/django,shaib/django,koordinates/django,monetate/django,ghickman/django,rsalmaso/django,blighj/django,wkschwartz/django,atul-bhouraskar/django,dsanders11/django,ghickman/django,MarkusH/django,googleinterns/django,shaib/django,koordinates/django,dsanders11/django,googleinterns/django,monetate/django,blighj/django,manhhomienbienthuy/django,MarkusH/django,adamchainz/django,wkschwartz/django,wkschwartz/django,manhhomienbienthuy/django,blighj/django,wkschwartz/django,rsalmaso/django,freakboy3742/django,felixxm/django,solarissmoke/django,freakboy3742/django,apollo13/django,rsalmaso/django,ghickman/django,adamchainz/django,monetate/django,googleinterns/django,takis/django,MarkusH/django,adamchainz/django,rsalmaso/django,felixxm/django,auvipy/django,django/django,takis/django,auvipy/django,django/django,elena/django,monetate/django,apollo13/django,dsanders11/django,adamchainz/django,freakboy3742/django,auvipy/django,manhhomienbienthuy/django,MarkusH/django,django/django,elena/django,felixxm/django,pauloxnet/django,koordinates/django,auvipy/django,solarissmoke/django,atul-bhouraskar/django,elena/django,shaib/django,atul-bhouraskar/django,ghickman/django,atul-bhouraskar/django,pauloxnet/django,takis/django,shaib/django