added go test app

tests/go/.godir

@@ -0,0 +1 @@
+go

tests/go/Procfile

@@ -0,0 +1 @@
+web: go

tests/go/web.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+    "fmt"
+    "net/http"
+    "os"
+)
+
+func main() {
+    http.HandleFunc("/", hello)
+    fmt.Println("listening...")
+    err := http.ListenAndServe(":"+os.Getenv("PORT"), nil)
+    if err != nil {
+      panic(err)
+    }
+}
+
+func hello(res http.ResponseWriter, req *http.Request) {
+    fmt.Fprintln(res, "hello, world")
+}