expire, trust et al, dead, describe: Support --json and --json-error-messages

For expire, the normal output is unchanged, but the --json output includes the uuid
in machine parseable form. Which could be very useful for this somewhat obscure
command. That needed ActionItemUUID to be implemented, which seemed like a lot
of work, but then ---

I had been going to skip implementing them for trust, untrust, dead, semitrust,
and describe, but putting the uuid in the json is useful information, it tells
what uuid git-annex picked given the input. It was not hard to support
these once ActionItemUUID was implemented.

Sponsored-By: the NIH-funded NICEMAN (ReproNim TR&D3) project

Command/Describe.hs

@@ -23,10 +23,10 @@ seek = withWords (commandAction . start)
 start :: [String] -> CommandStart
 start (name:description) | not (null description) = do
 	u <- Remote.nameToUUID name
+	let ai = ActionItemUUID u (UnquotedString name)
 	starting "describe" ai si $
 		perform u $ unwords description
   where
-	ai = ActionItemOther (Just (UnquotedString name))
 	si = SeekInput [name]
 start _ = giveup "Specify a repository and a description."