Auto-subscribe user to repository when they commit/tag to it (#7657)

* Add support for AUTO_WATCH_ON_CHANGES and AUTO_WATCH_ON_CLONE

* Update models/repo_watch.go

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Round up changes suggested by lafriks

* Added changes suggested from automated tests

* Updated deleteUser to take RepoWatchModeDont into account, corrected inverted DefaultWatchOnClone and DefaultWatchOnChanges behaviour, updated and added tests.

* Reinsert import "github.com/Unknwon/com" on http.go

* Add migration for new column `watch`.`mode`

* Remove serv code

* Remove WATCH_ON_CLONE; use hooks, add integrations

* Renamed watch_test.go to repo_watch_test.go

* Correct fmt

* Add missing EOL

* Correct name of test function

* Reword cheat and ini descriptions

* Add update to migration to ensure column value

* Clarify comment

Co-Authored-By: zeripath <art27@cantab.net>

* Simplify if condition

integrations/repo_watch_test.go

@@ -0,0 +1,24 @@
+// Copyright 2019 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 integrations
+
+import (
+	"net/url"
+	"testing"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+func TestRepoWatch(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, giteaURL *url.URL) {
+		// Test round-trip auto-watch
+		setting.Service.AutoWatchOnChanges = true
+		session := loginUser(t, "user2")
+		models.AssertNotExistsBean(t, &models.Watch{UserID: 2, RepoID: 3})
+		testEditFile(t, session, "user3", "repo3", "master", "README.md", "Hello, World (Edited for watch)\n")
+		models.AssertExistsAndLoadBean(t, &models.Watch{UserID: 2, RepoID: 3, Mode: models.RepoWatchModeAuto})
+	})
+}