Add support to configure webhook_timeout in gitlab.yaml

Created by: wesgurn

Our Gitlab instance needed the ability to increase the webhook_timeout used by HTTParty. It was hardcoded at 10 and I moved it to a gitlab.yaml file as a config variable

Webhook settings

webhook_timeout: 30 # default: 10 - Number of seconds to wait for HTTP response after sending webhook HTTP POST request

doc/update/4.1-to-4.2.md

@@ -12,15 +12,15 @@
 cd /home/gitlab/gitlab/
 # Get latest code
-sudo -u gitlab git fetch
-sudo -u gitlab git checkout 4-2-stable
+sudo -u gitlab -H git fetch
+sudo -u gitlab -H git checkout 4-2-stable
 # Install libs
-sudo -u gitlab bundle install --without development test postgres --deployment
+sudo -u gitlab -H bundle install --without development test postgres --deployment
 # update db
-sudo -u gitlab bundle exec rake db:migrate RAILS_ENV=production
+sudo -u gitlab -H bundle exec rake db:migrate RAILS_ENV=production
 ```