Update.1 ex-preinstalled activities: stable vs unstable

[Morgan Collett]

> I was going to make a .xo from git (jhbuild) and stick that up on the
> wiki when I saw there are newer commits in git than release 19, and that
> got me wondering:

I added a download link to Pippy on [[Activities]] to
http://dev.laptop.org/~cjb/pippy/Pippy-19.xo.

The formerly-preinstalled activities have either no download link or a
significantly out of date version. I updated a few more but gave up.

Aside from the stable/unstable issue, I propose that activity authors
put .xos from their public_rpms in their public_html and maintain the
links on [[Activities]] and the activities' wiki pages to the
appropriate version there.

Morgan