Read bind port from the environment

Main.hs

@@ -2,8 +2,14 @@
 module Main where
 
 import Application
+
+import Control.Applicative
+import System.Environment
 import Network.Wai.Handler.Warp
 import Network.Wai.Middleware.RequestLogger
 
+
 main :: IO ()
-main = app (run 3000 . logStdout)
+main = do
+  port <- maybe 3000 read <$> lookupEnv "PORT"
+  app (run port . logStdout)