only add :port to appRoot if not 80

yesod/scaffold/Settings.hs.cg

@@ -91,10 +91,14 @@ loadConfig env = do
     return $ AppConfig {
       appEnv = env
     , appPort = read portS
-    , appRoot = pack (hostS ++ ":" ++ portS)
+    , appRoot = maybeAddPort hostS portS
     , connectionPoolSize = read connectionPoolSizeS
     }
 
+    where
+        maybeAddPort :: String -> String -> Text
+        maybeAddPort h p = pack $ if p == "80" then h else h ++ ":" ++ p
+
 -- Static setting below. Changing these requires a recompile
 
 -- | The location of static files on your system. This is a file system