ADD get commit diff api

app/views/repositories/_commit_author.json.jbuilder

@@ -0,0 +1,8 @@
+if user
+  json.id user.id
+  json.login user.login
+  json.name user.real_name
+  json.image_url url_to_avatar(user)
+else
+  json.nil!
+end

app/views/repositories/commit.json.jbuilder

@@ -0,0 +1,26 @@
+json.key_format! camelize: :lower
+json.additions @custom_commit['TotalAddition']
+json.deletions @custom_commit['TotalDeletion']
+json.sha @commit['sha']
+json.url request.url
+json.commit do
+  @commit['commit'].delete('url')
+  json.author @commit['commit']['author']
+  json.committer @commit['commit']['committer']
+  json.tree do
+    @commit['commit']['tree']['sha']
+  end
+end
+json.author do
+  json.partial! 'commit_author', user: render_commit_author(@commit['author'])
+end
+json.committer do
+  json.partial! 'commit_author', user: render_commit_author(@commit['committer'])
+end
+
+json.parents @commit['parents'] do |parent|
+  json.sha parent['sha']
+  json.url EduSetting.get('host_name') + commit_repository_path(@repo, parent['sha'])
+end
+
+json.files @custom_commit['Files']