This is more accurate than 'Site Default'.  When there's no page theme,
users looking at the page don't necessarily see the site default theme
if their institution has overridden it for them.

Change-Id: I60e2de14b5812c4ceef6b017c7636d3e9454bc85
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>