Add podcast email field for RSS itunes:owner tag

Enables users to set a podcast contact email from the dashboard
settings. This email is included in the RSS feed as
itunes:owner/itunes:email, which podcast directories like Spotify
and Apple Podcasts require for indexing and verification.

handler/rss.go

@@ -26,11 +26,18 @@ type rssChannel struct {
 	Description string          `xml:"description"`
 	Language    string          `xml:"language"`
 	Author      string          `xml:"itunes:author,omitempty"`
+	ItunesOwner *rssItunesOwner `xml:"itunes:owner,omitempty"`
 	Image       *rssImage       `xml:"image,omitempty"`
 	ItunesImage *rssItunesImage `xml:"itunes:image,omitempty"`
+	ItunesType  string          `xml:"itunes:type,omitempty"`
 	Items       []rssItem       `xml:"item"`
 }
 
+type rssItunesOwner struct {
+	Name  string `xml:"itunes:name"`
+	Email string `xml:"itunes:email"`
+}
+
 type rssImage struct {
 	URL   string `xml:"url"`
 	Title string `xml:"title"`
@@ -132,6 +139,14 @@ func (h *RSSHandler) ServeRSS(w http.ResponseWriter, r *http.Request) {
 		chanItunesImage = &rssItunesImage{Href: h.fullURL(user.PodcastImage)}
 	}
 
+	var owner *rssItunesOwner
+	if user.PodcastEmail != "" || author != "" {
+		owner = &rssItunesOwner{
+			Name:  author,
+			Email: user.PodcastEmail,
+		}
+	}
+
 	feed := rssFeed{
 		Version:  "2.0",
 		ItunesNS: "http://www.itunes.com/dtds/podcast-1.0.dtd",
@@ -141,6 +156,7 @@ func (h *RSSHandler) ServeRSS(w http.ResponseWriter, r *http.Request) {
 			Description: title,
 			Language:    "en-us",
 			Author:      author,
+			ItunesOwner: owner,
 			Image:       chanImage,
 			ItunesImage: chanItunesImage,
 			Items:       items,