[sugar] sugar-jhbuild activities path changed

[Morgan Collett]

Marco changed the activities path in sugar from share/activities to
share/sugar/activities.

I pushed this change to the jhbuild setup too so activities install in
the new location.

If you get no activities when running in jhbuild, remember to build
the activities again.

(etoys and calculate need changes to their Makefile(.in) to get the
install path correct.)