cleanup (plugin): deprecated starter plugin

That plugin wouldn't work as expected and result in some angry email
from people who gave it a try so I'm getting rid of it to focus on the
other core plugin that make more sense for the project

server/plugin/plg_starter_web/index.go

@@ -1,10 +0,0 @@
-package plg_starter_web
-
-import (
-	. "github.com/mickael-kerjean/filestash/server/common"
-)
-
-func init() {
-	Hooks.Register.Starter(WebServer)
-	// Hooks.Register.Hook() // letsencrypt hook
-}

server/plugin/plg_starter_web/server.go

@@ -1,32 +0,0 @@
-package plg_starter_web
-
-import (
-	"github.com/gorilla/mux"
-	. "github.com/mickael-kerjean/filestash/server/common"
-	"golang.org/x/crypto/acme/autocert"
-	"net/http"
-	"path/filepath"
-)
-
-func WebServer(r *mux.Router) {
-	certManager := autocert.Manager{
-		Prompt:     autocert.AcceptTOS,
-		HostPolicy: autocert.HostWhitelist(Config.Get("general.host").String()),
-		Cache:      autocert.DirCache(filepath.Join(CERT_PATH, "ssl")),
-	}
-	go func() {
-		if err := http.ListenAndServe(":http", certManager.HTTPHandler(nil)); err != nil {
-			Log.Error("error: %v", err)
-			return
-		}
-	}()
-	srv := &http.Server{
-		Addr:      ":https",
-		Handler:   r,
-		TLSConfig: certManager.TLSConfig(),
-	}
-	if err := srv.ListenAndServeTLS("", ""); err != nil {
-		Log.Error("error: %v", err)
-		return
-	}
-}