Unless busybox doesn't support readlink -f, then it just uses readlink and
symlinking won't work. Also, OSX has no readlink -f so not done there.
Thanks, jlebar.
* webapp: Support using git-annex on a remote server, which was installed
from the standalone tarball or OSX app, and so does not have
git-annex in PATH (and may also not have git or rsync in PATH).
* standalone tarball, OSX app: Install a ~/.ssh/git-annex-wrapper, which
can be used to run git-annex, git, rsync, etc.
