So far, handling connecting to git-annex-shell notifychanges, and
pulling immediately when a change is pushed to a remote.
A little bit buggy (crashes after the first pull), but it already works!
This commit was sponsored by Mark Sheppard.
This will be used by the remote-daemon to quickly tell when changes have
been pushed from some other repository into a ssh remote.
Adjusted the remote-daemon protocol to communicate changed shas, rather
than git branch refs. This way, it can easily check if a sha is new.
This commit was sponsored by Carlos Trijueque Albarran.
