Add an extra space when displaying package version lists

eg: "xmonad [0.1, 0.2, 0.3]" rather than "xmonad [0.1,0.2,0.3]"
it's just a tad easier to read.

cabal-install/Hackage/List.hs

@@ -48,7 +48,7 @@ list cfg pats = do
 
 doList :: [PkgInfo] -> IO ()
 doList ps = do   
-    putStr $ padTo 35 $ pkgName (package d) ++ " [" ++ concat (intersperse "," versions) ++ "]"
+    putStr $ padTo 35 $ pkgName (package d) ++ " [" ++ concat (intersperse ", " versions) ++ "]"
     putStrLn syn
     where
     info = last ps