Allow Gogs to run from a suburl behind a reverse proxy. e.g. http://mydomain.com/gogs/

Conflicts:
	modules/setting/setting.go

Conflicts:
	templates/repo/release/list.tmpl
	templates/user/dashboard/dashboard.tmpl

Conflicts:
	routers/repo/setting.go

routers/home.go

@@ -33,7 +33,7 @@ func Home(ctx *middleware.Context) {
 	// Check auto-login.
 	uname := ctx.GetCookie(setting.CookieUserName)
 	if len(uname) != 0 {
-		ctx.Redirect("/user/login")
+		ctx.Redirect(setting.AppRootSubUrl + "/user/login")
 		return
 	}