Fix mangling of --json output of utf-8 characters when not running in a utf-8 locale

As long as all code imports Utility.Aeson rather than Data.Aeson,
and no Strings that may contain utf-8 characters are used for eg, object
keys via T.pack, this is guaranteed to fix the problem everywhere that
git-annex generates json.

It's kind of annoying to need to wrap ToJSON with a ToJSON', especially
since every data type that has a ToJSON instance has to be ported over.
However, that only took 50 lines of code, which is worth it to ensure full
coverage. I initially tried an alternative approach of a newtype FileEncoded,
which had to be used everywhere a String was fed into aeson, and chasing
down all the sites would have been far too hard. Did consider creating an
intentionally overlapping instance ToJSON String, and letting ghc fail
to build anything that passed in a String, but am not sure that wouldn't
pollute some library that git-annex depends on that happens to use ToJSON
String internally.

This commit was supported by the NSF-funded DataLad project.

Remote.hs

@@ -57,9 +57,8 @@ module Remote (
 ) where
 
 import Data.Ord
-import Data.Aeson
 import qualified Data.Map as M
-import qualified Data.Text as T
+import qualified Data.Vector as V
 
 import Annex.Common
 import Types.Remote
@@ -74,6 +73,7 @@ import Config
 import Config.DynamicConfig
 import Git.Types (RemoteName)
 import qualified Git
+import Utility.Aeson
 
 {- Map from UUIDs of Remotes to a calculated value. -}
 remoteMap :: (Remote -> v) -> Annex (M.Map UUID v)
@@ -197,7 +197,7 @@ prettyPrintUUIDsDescs header descm uuids =
 
 {- An optional field can be included in the list of UUIDs. -}
 prettyPrintUUIDsWith
-	:: ToJSON v
+	:: ToJSON' v
 	=> Maybe String 
 	-> String 
 	-> M.Map UUID RemoteName
@@ -206,7 +206,7 @@ prettyPrintUUIDsWith
 	-> Annex String
 prettyPrintUUIDsWith optfield header descm showval uuidvals = do
 	hereu <- getUUID
-	maybeShowJSON $ JSONChunk [(header, map (jsonify hereu) uuidvals)]
+	maybeShowJSON $ JSONChunk [(header, V.fromList $ map (jsonify hereu) uuidvals)]
 	return $ unwords $ map (\u -> "\t" ++ prettify hereu u ++ "\n") uuidvals
   where
 	finddescription u = M.findWithDefault "" u descm
@@ -224,11 +224,11 @@ prettyPrintUUIDsWith optfield header descm showval uuidvals = do
 			Nothing -> s
 			Just val -> val ++ ": " ++ s
 	jsonify hereu (u, optval) = object $ catMaybes
-		[ Just (T.pack "uuid", toJSON $ fromUUID u)
-		, Just (T.pack "description", toJSON $ finddescription u)
-		, Just (T.pack "here", toJSON $ hereu == u)
+		[ Just (packString "uuid", toJSON' $ fromUUID u)
+		, Just (packString "description", toJSON' $ finddescription u)
+		, Just (packString "here", toJSON' $ hereu == u)
 		, case (optfield, optval) of
-			(Just field, Just val) -> Just (T.pack field, toJSON val)
+			(Just field, Just val) -> Just (packString field, toJSON' val)
 			_ -> Nothing
 		]