add http server & test

e2e/basic.hurl

@@ -0,0 +1,3 @@
+GET http://localhost:8080/foo
+HTTP 200
+`Hello, "/foo"`

main.go

@@ -1,7 +1,15 @@
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"html"
+	"log"
+	"net/http"
+)
 
 func main() {
-	fmt.Println("Hello world!")
+	http.HandleFunc("/foo", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
+	})
+	log.Fatal(http.ListenAndServe(":8080", nil))
 }