Merge branch 'webhooks' into 'master'

CHANGELOG

app/helpers/search_helper.rb

app/services/git_push_service.rb

app/views/layouts/nav/_project_settings.html.haml

app/views/projects/hooks/index.html.haml

doc/README.md

doc/hooks/custom_hooks.md

doc/raketasks/README.md

doc/raketasks/web_hooks.md

doc/security/README.md

doc/security/webhooks.md

doc/web_hooks/web_hooks.md

features/steps/project/active_tab.rb

features/steps/project/hooks.rb

lib/gitlab/push_data_builder.rb

lib/tasks/gitlab/web_hook.rake

spec/models/hooks/service_hook_spec.rb

spec/models/hooks/web_hook_spec.rb

spec/services/git_push_service_spec.rb

spec/services/git_tag_push_service_spec.rb