[Systems] Cleaned up wiki cursors

[Bernie Innocenti]

Yesterday I noticed that the wiki was loading non-SSL resources when
accessed through https://. So I discovered that our custom CSS was
loading the Sugar cursors from http://wiki-devel.sugarlabs.org/...

As I was there, I've scaled down the cursors to 75% of their original
size, so they don't look huge compared to the system cursors.

Thanks for fixing the hot-spots, Frederick! ImageMagick's convert
program looses them. It would be interesting to check if the Windows
Chromium bug is still present.

-- 
Bernie Innocenti
Sugar Labs Infrastructure Team
http://wiki.sugarlabs.org/go/Infrastructure_Team