clean up read/show abuse

Avoid ever using read to parse a non-haskell formatted input string.

show :: Key is arguably still show abuse, but displaying Keys as filenames
is just too useful to give up.

Types/TrustLevel.hs

@@ -17,14 +17,4 @@ import Types.UUID
 data TrustLevel = SemiTrusted | UnTrusted | Trusted
 	deriving Eq
 
-instance Show TrustLevel where
-        show SemiTrusted = "?"
-        show UnTrusted = "0"
-        show Trusted = "1"
-
-instance Read TrustLevel where
-        readsPrec _ "1" = [(Trusted, "")]
-        readsPrec _ "0" = [(UnTrusted, "")]
-	readsPrec _ _ = [(SemiTrusted, "")]
-
 type TrustMap = M.Map UUID TrustLevel