make bare repo on server

I think this makes sense.. Unless the assistant is running on the server,
the repo won't be updated, so it might as well be bare.

Non-bare repos will be handled by the pairing configurator, later.

Assistant/WebApp/Configurators/Ssh.hs

@@ -270,7 +270,7 @@ getMakeSshR sshdata = do
 		makerepo
 			| rsyncOnly sshdata = []
 			| otherwise =
-				[ "git init"
+				[ "git init --bare --shared"
 				, "git annex init"
 				]
 		makeAuthorizedKeys =