Get basic HTTP server working

web/responses.go

@@ -0,0 +1,15 @@
+package web
+
+//go:generate easyjson -all responses.go
+
+// ShortenedResponse contains shortened URL info.
+type ShortenedResponse struct {
+	UID      string `json:"uid"`
+	ShortURL string `json:"short_url"`
+	URL      string `json:"url"`
+}
+
+// ErrorResponse contains error info.
+type ErrorResponse struct {
+	Error string `json:"error"`
+}