add git-annex-shell commit

Eventually, git-annex might try running this after making changes to
a remote. I have not yet thought of a good way for it to tell which
remotes it needs to run it on though. It can't just do it when
shutting down a cached ssh connection, because ssh connection caching
is optional, and that would not handle local remotes not accessed over ssh
either.

Command/Commit.hs

@@ -0,0 +1,23 @@
+{- git-annex command
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.Commit where
+
+import Command
+import qualified Annex.Branch
+
+def :: [Command]
+def = [command "commit" paramNothing seek
+	"commits any staged changes to the git-annex branch"]
+
+seek :: [CommandSeek]
+seek = [withNothing start]
+
+start :: CommandStart
+start = next $ next $ do
+	Annex.Branch.commit "update"
+	return True