Use HTTPS protocol for arc

.arcconfig

 {
 	"project_id" : "Blender Addons",
-	"conduit_uri" : "http://developer.blender.org/",
+	"conduit_uri" : "https://developer.blender.org/",
 	"git.default-relative-commit" : "origin/master",
 	"arc.land.update.default" : "rebase"
 }