First pass at YP registration/configuration (#209)

* Spike: Ping YP service with instance details

* WIP: Add to the config to support YP

* Add YP response endpoint

* Handle YP errors. Use config. Off by default

* Show message about YP support on launch

* Add animated gif preview when generating thumb

* Increase quality of preview gif and only create it if YP is enabled

* Do not allow re-registration by clearing the key

* Make large and small logos actually structured

* Change log level

* Fix default YP service URL

* Point to default hostname

* Set default value for YP to false

controllers/index.go

@@ -69,7 +69,7 @@ func handleScraperMetadataPage(w http.ResponseWriter, r *http.Request) {
 	tmpl := template.Must(template.ParseFiles(path.Join("static", "metadata.html")))
 
 	fullURL, err := url.Parse(fmt.Sprintf("http://%s%s", r.Host, r.URL.Path))
-	imageURL, err := url.Parse(fmt.Sprintf("http://%s%s", r.Host, config.Config.InstanceDetails.Logo["large"]))
+	imageURL, err := url.Parse(fmt.Sprintf("http://%s%s", r.Host, config.Config.InstanceDetails.Logo.Large))
 
 	status := core.GetStatus()