fix some mixed space+tab indentation

This fixes all instances of " \t" in the code base. Most common case
seems to be after a "where" line; probably vim copied the two space layout
of that line.

Done as a background task while listening to episode 2 of the Type Theory
podcast.

Assistant/Gpg.hs

@@ -20,7 +20,7 @@ newUserId :: IO UserId
 newUserId = do
 	oldkeys <- secretKeys
 	username <- myUserName
-  	let basekeyname = username ++ "'s git-annex encryption key"
+	let basekeyname = username ++ "'s git-annex encryption key"
 	return $ Prelude.head $ filter (\n -> M.null $ M.filter (== n) oldkeys)
 		( basekeyname
 		: map (\n -> basekeyname ++ show n) ([2..] :: [Int])