[Cs5500] update about svn repo

[liao yuncheng]

Hi professor,

I've done more research on sourceforge. It seems they need to obey the
rule of "Open Source".

"Read permissions are granted to all users (including anonymous
access). In the spirit of Open Source, source code should be available
to everyone, so no means is provided to remove read access from a
repository."

Which means we can not set up a secret repo in sorceforge, also I
think the same rule will be highly possible to apply on other public
and free svn providers.

One question would be if we want public to access our teacher avatar,
we also open the door for undergrad students.

I think we can do it like this:

we set up the repository on sourceforge, and only put the scg WITHOUT
teacher avatar. And we can set up another secrete repo for teacher
avatars somewhere else.

Tell me what you guys think,

Thank you the best,
Vincent Liao