basic support for git-remote-daemon protocol
tiny little protocol between git-remote-daemon and git-annex-shell

Subset of the git-remote-daemon protocol.
git-annex-shell: Added notifychanges command.

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.
Merge commit '402551561624cd83ec8c15d09411210111edc557'
credit
Fix nautilus script installation to not crash when the nautilus script dir does not exist. Instead, only install scripts when the directory already exists.

nautilus creates this directory each time run, so this avoids putting cruft
in user's home
Merge branch 'master' of ssh://git-annex.branchable.com
close
Make ~/.config/nautilus/scripts; Nautilus doesn’t make it