Extend Package to include id

This commit
1. rename Package with PackageBaseName
2. Pacakge = (PackageBaseName, Maybe String) to save its id
3. Expose packages with id if available

Language/Haskell/GhcMod/Debug.hs

@@ -41,7 +41,7 @@ debug opt cradle fileName = do
       , "Cabal file:          " ++ cabalFile
       , "GHC options:         " ++ unwords gopts
       , "Include directories: " ++ unwords incDir
-      , "Dependent packages:  " ++ intercalate ", " pkgs
+      , "Dependent packages:  " ++ (intercalate ", " $ map fst pkgs)
       , "Fast check:          " ++ if fast then "Yes" else "No"
       ]
   where