Implement Default Webhooks (#4299)

Partially implement #770.
Add "Default Webhooks" page in site admin UI.
Persist to the existing webhooks table, but store with RepoID=0 and OrgID=0.
Upon repo creation, copy the set of default webhooks into the new repo.

routers/admin/hooks.go

@@ -0,0 +1,47 @@
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package admin
+
+import (
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+const (
+	// tplAdminHooks template path for render hook settings
+	tplAdminHooks base.TplName = "admin/hooks"
+)
+
+// DefaultWebhooks render admin-default webhook list page
+func DefaultWebhooks(ctx *context.Context) {
+	ctx.Data["Title"] = ctx.Tr("admin.hooks")
+	ctx.Data["PageIsAdminHooks"] = true
+	ctx.Data["BaseLink"] = setting.AppSubURL + "/admin/hooks"
+	ctx.Data["Description"] = ctx.Tr("admin.hooks.desc")
+
+	ws, err := models.GetDefaultWebhooks()
+	if err != nil {
+		ctx.ServerError("GetWebhooksDefaults", err)
+		return
+	}
+
+	ctx.Data["Webhooks"] = ws
+	ctx.HTML(200, tplAdminHooks)
+}
+
+// DeleteDefaultWebhook response for delete admin-default webhook
+func DeleteDefaultWebhook(ctx *context.Context) {
+	if err := models.DeleteDefaultWebhook(ctx.QueryInt64("id")); err != nil {
+		ctx.Flash.Error("DeleteDefaultWebhook: " + err.Error())
+	} else {
+		ctx.Flash.Success(ctx.Tr("repo.settings.webhook_deletion_success"))
+	}
+
+	ctx.JSON(200, map[string]interface{}{
+		"redirect": setting.AppSubURL + "/admin/hooks",
+	})
+}