Fix memory leak in Haskell binding and simpily example (#86)

haskell/Ruapu.hs

@@ -3,7 +3,7 @@
 module Ruapu where
 
 import Foreign
-import Foreign.C.String (CString, newCAString, peekCAString)
+import Foreign.C.String (CString, withCAString, peekCAString)
 
 foreign import ccall "ruapu.c ruapu_init"
     init :: IO ()
@@ -15,7 +15,7 @@ foreign import ccall "ruapu.c ruapu_rua"
     cRua :: IO (Ptr CString)
 
 supports :: String -> IO Bool
-supports xs = (newCAString xs) >>= cSupports
+supports = flip withCAString cSupports
 
 rua :: IO [String]
 rua = cRua >>= peekArray0 nullPtr >>= mapM peekCAString