Git statistics in Activity tab (#4724)

* Initial implementation for git statistics in Activity tab

* Create top user by commit count endpoint

* Add UI and update src-d/go-git dependency

* Add coloring

* Fix typo

* Move git activity stats data extraction to git module

* Fix message

* Add git code stats test

modules/git/repo_stats_test.go

@@ -0,0 +1,35 @@
+// 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 git
+
+import (
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRepository_GetCodeActivityStats(t *testing.T) {
+	bareRepo1Path := filepath.Join(testReposDir, "repo1_bare")
+	bareRepo1, err := OpenRepository(bareRepo1Path)
+	assert.NoError(t, err)
+
+	timeFrom, err := time.Parse(time.RFC3339, "2016-01-01T00:00:00+00:00")
+
+	code, err := bareRepo1.GetCodeActivityStats(timeFrom, "")
+	assert.NoError(t, err)
+	assert.NotNil(t, code)
+
+	assert.EqualValues(t, 8, code.CommitCount)
+	assert.EqualValues(t, 2, code.AuthorCount)
+	assert.EqualValues(t, 8, code.CommitCountInAllBranches)
+	assert.EqualValues(t, 10, code.Additions)
+	assert.EqualValues(t, 1, code.Deletions)
+	assert.Len(t, code.Authors, 2)
+	assert.Contains(t, code.Authors, "tris.git@shoddynet.org")
+	assert.EqualValues(t, 3, code.Authors["tris.git@shoddynet.org"])
+	assert.EqualValues(t, 5, code.Authors[""])
+}