Bug 21583: Don't use Asset.js for external script files

Bug 21583: Don't use Asset.js for external script files

To test:
1 - Enable Novelist in staff client:
    NovelistSelectStaffEnabled: Add
    NovelistSelectStaffProfile: anything
    NovelistSelectPassword: anything
    ( these don't need to be valid, just not blank )
2 - Pull up a record detail page in staff client
3 - View page source - search for ns2init.js
4 - You won't find it
5 - Apply patch
6 - Reload details
7 - Search page source for ns2init.js
8 - It loaded! Huzzah!

Signed-off-by: George Williams <george@nekls.org>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>